c++ programming language 1 week...1 c++ programming language 1st week all computer systems consist...

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C++ Programming Language 1st week

All computer systems consist of similar hardware devices and software components.

Hardware: Hardware refers to the physical components that a computer is made of. A

computer is not an individual device, but a system of devices. A typical computer system

consists of the following major components:

1. The central processing unit (CPU)

2. Main memory (RAM)

3. Secondary storage devices

4. Input devices

5. Output devices

Software: Software refers to the programs that run on a computer. There are two general

categories of software: operating systems and application software. An operating system is a

set of programs that manages the computer's hardware devices and controls their processes.

Application software refers to program that the computer useful to the user. These programs

solve specific problems or perform general operations that satisfy the needs of the user.

Programming Languages

There are two categories of programming languages: low level and high level. A low

level language is close to the level of the computer, which means it resembles the numeric

machine language of the computer more than natural language of humans. The easiest

languages for people to learn are high level language. They are called "high level" because

they are closer to the level of human readability than computer-readability like C++.

How C++ Programming Works

The C++ programming language is a popular and widely used programming language for

creating computer programs. Programmers around the world embrace C++ because it gives

maximum control and efficiency to the programmer.

If you are a programmer, or if you are interested in becoming a programmer, there are a

couple of benefits you gain from learning C++:

You will be able to read and write code for a large number of platforms -- everything

from microcontrollers to the most advanced scientific systems can be written in C++,

and many modern operating systems are written in C++.

C++ is an object oriented language. C++ is an extension of C, C++ also includes

several other improvements to the C language, including an extended set of library

routines.

We will walk through the entire language and show you how to become a C++

programmer, starting at the beginning. You will be amazed at all of the different things

you can create once you know C++!

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What is C++?

C++ is a computer programming language. That means that you can use C++ to create

lists of instructions for a computer to follow. C++ is one of thousands of programming

languages currently in use. It gives programmers maximum control and efficiency. C++ is an

easy language to learn. It is a bit more cryptic in its style than some other languages, but you

get beyond that fairly quickly.

C++ is what is called a compiled language. This means that once you write your C++

program, you must run it through a C++ compiler to turn your program into an executable

that the computer can run (execute). The C++ program is the human-readable form, while

the executable that comes out of the compiler is the machine-readable and executable form.

When a C++ program is written, it must be typed into the computer and saved to a

file. A text editor, which is similar to a word processing program, is used for this task. The

statements written by the programmer are called source code, and the file they are saved in is

called the source file. After the source code is saved to a file, the process of translating it to

machine language can begin.

During the first phase of this process, a program called the preprocessor reads the

source code. The preprocessor searches for special lines that begin with the (#) symbol. These

lines contain commands that cause the preprocessor to modify the source code in some way

as we will see later.

During the next phase the compiler steps through the preprocessed source code,

translating each source code instruction into the appropriate machine language instruction.

This process will uncover any syntax errors that may be in the program. Syntax errors are

illegal uses of keywords, operators, punctuation, and other language elements. If the program

is free of syntax errors, the compiler stores the translated machine language instructions,

which are called object code, in an object file.

Although an object file contains machine language instructions, it is not a complete

program, because C++ is conveniently equipped with a library of prewritten code for

performing common operations or sometimes difficult tasks. For example, the library

contains mathematical functions, such as calculating the square root of a number. The

collection of code, called the run time library, is extensive. Programs almost always use

some part of it. When the compiler generates an object file, however, it does not include

machine code for any run time library routines the programmer might have used. During the

last phase of the translation process, another program called the linker combines the object

file with the necessary library routines. Once the linker has finished with this step, an

executable file is created. The executable file contains machine language instructions, or

executable code, and is ready to run on the computer.

Libraries

Libraries are very important in C++ because the C++ language supports only the most basic

features that it needs. C++ does not even contain I/O functions to read from the keyboard and

write to the screen. Anything that extends beyond the basic language must be written by a

programmer. The resulting chunks of code are often placed in libraries to make them easily

reusable. We have seen the standard I/O, or stdio, library already: Standard libraries exist for

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standard I/O, math functions, string handling, time manipulation, and so on. You can use

libraries in your own programs to split up your programs into modules. This makes them

easier to understand, test, and debug, and also makes it possible to reuse code from other

programs that you write.

The Simplest C++ Program

Let's start with the simplest possible C++ program and use it both to understand the basics of

C++ and the C++ compilation process.

#include <stdio.h> int main() { printf("Hello"); return 0; }

When executed, this program instructs the computer to print out the line "Hello" -- then the

program quits. You can't get much simpler than that!

You should see the output "Hello" when you run the program. Here is what happened when

you compiled the program:

If you mistype the program, it either will not compile or it will not run. If the program does

not compile or does not run correctly, edit it again and see where you went wrong in your

typing. Fix the error and try again.

The Simplest C++ Program: What's Happening?

This C++ program starts with #include <stdio.h>. This line includes the "standard I/O

library" into your program. The standard I/O library lets you read input from the keyboard

(called "standard in"), write output to the screen (called "standard out"), process text files

stored on the disk, and so on. It is an extremely useful library. C has a large number of

standard libraries like stdio, including string, time and math libraries. A library is simply

a package of code that someone else has written to make your life easier

The line int main() declares the main function. Every C++ program must have a function

named main somewhere in the code. At run time, program execution starts at the first line

of the main function.

In C++, the { and } symbols mark the beginning and end of a block of code. In this case,

the block of code making up the main function contains two lines.

The printf statement in C++ allows you to send output to standard out (for us, the

screen). The portion in quotes is called the format string and describes how the data is to

be formatted when printed. The format string can contain string literals such as "Hello",

symbols for carriage returns (\n), and operators as placeholders for variables.

The return 0; line causes the function to return an error code of 0 (no error) to the shell

that started execution.

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We can little update the previous program to become

#include <stdio.h>

#include <conio.h>

int main()

{

Clrscr();

printf("Hello");

getch();

return 0;

}

#include <conio.h>. This line includes the "console I/O library" into your program.

clrscr() clears the current text window and places the cursor in the upper left-hand corner

(at position 1,1).

getch() reads a single character directly from the keyboard, without echoing to the screen.

To output colored text, you can use cprintf() function, and the program becomes:

#include <conio.h>

int main(void)

{

/* clear the screen */

clrscr();

textattr(0x34);

/* output some text */

cprintf("Hello");

/* wait for a key */

getch();

return 0;

}

cprintf sends formatted output to the text window on the screen

textattr this functions work for functions that produce text-mode output directly to the

screen (console output functions).

Declaration:

void textattr(int newattr);

Remarks:

textattr sets both the foreground and background colors in a single call.

(Normally, you set the attributes with textcolor and textbackground.)

textbackground selects the background color.

textcolor selects the foreground character color.

These functions do not affect any characters currently on the screen. Once you have called

one of these three functions, all subsequent functions using direct video output (such as

cprintf) will use the new attributes or colors.

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If you use symbolic color constants, the following limitations apply to the background colors

you select:

- You can only select one of the first eight colors (0--7).

- With textattr, you must shift the selected background color left by 4 bits to move it into

the correct "bbb" bit positions.

NOTE: If you use the symbolic color constants, you must include CONIO.H.

Newattr

This is how color information is encoded in the newattr argument of textattr: 7 6 5 4 3 2 1 0

B b b b f f f f

In this 8-bit newattr parameter,

ffff = 4-bit foreground color (0 to 15)

bbb = 3-bit background color (0 to 7)

B = blink-enable bit

Blinking characters

If the blink-enable bit is on, the character blinks. To turn the bit on in a call to textattr, you

add the constant BLINK to the attribute.

To make the characters blink in a call to textcolor, you add 128 to the foreground color. The

predefined constant BLINK exists for this purpose; for example,

textcolor(CYAN + BLINK);

Light colors

Some monitors do not recognize the intensity signal used to create the eight "light" colors (8-

15). On such monitors, the light colors are displayed as their "dark" equivalents (0-7).

Also, systems that do not display in color can treat these numbers as shades of one color,

special patterns, or special attributes (such as underlined, bold, italics, etc.).

Exactly what you'll see on such systems depends on your hardware.

Another method to output your message, and the program becomes:

#include <iostream.h>

int main()

{

cout << "Hello";

return 0;

}

#include <iostrem.h> tells the preprocessor to include the iostream standard file. This

specific file (iostream) includes the declarations of the basic standard input-output library

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in C++, and it is included because its functionality is going to be used later in the

program.

cout << "Hello"; This line is a C++ statement. A statement is a simple or compound

expression that can actually produce some effect. In facts, this statement performs the

only action that generates a visible effect in our first program. cout represents the

standard output stream in C++, and the meaning of the entire statement is to insert a

sequence of characters (in this case, the Hello sequence of characters) into the standard

output stream (which usually is the screen).

To output multiple lines

#include <stdio.h> #include <conio.h> int main() { Clrscr(); printf("Hello"); printf("Nice to meet you"); getch(); return 0; }

The output becomes:

Hellonice to meet you

You can use \n for newline at the end of the 1st message, so that the 2nd

message appear in the next line, and the program becomes:

#include <stdio.h> #include <conio.h> int main() { Clrscr(); printf("Hello\n"); printf("Nice to meet you"); getch(); return 0; }

The output becomes:

Hello

nice to meet you

which is the same as

#include <stdio.h> #include <conio.h> int main() { Clrscr(); printf("Hello\nNice to meet you"); getch(); return 0; }

To output multiple lines using cout

#include <iostream.h> int main() { Cout << "Hello\nNice to meet you"; return 0; }

You may also use the endl manipulator to add a new line:

#include <iostream.h> int main() { Cout << "Hello"<<endl<<"Nice to meet you"; return 0; }

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Comments

Comments may be of the form:

// comment

or

/* comment */

The first form allows a trailing comment on a single line, while the second form allows

comments that span multiple lines.

Comments may appear anywhere.

Function Declarations

Provides the full definition of a function, while

storage_class type identifier (formal_argument_list);

provides a prototype of a function which may be used to provide code which uses the

function with the minimal essential parts of the definition to permit compilation. In the

prototype the formal_argument_list must contain the types, but need not contain names for

the formal arguments.

In older versions of C++, different syntax was used to declare formal arguments, placing

them after the closing parenthesis and before the function body.

Example:

Void main(void);

Void main(void)

{

}

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Constants and Variables 2nd

week

Constants are data items whose values cannot change while the program is running.

Literals

Literals are used to express particular values within the source code of a program. We have

already used these previously to give concrete values to variables or to express message we

wanted our programs to print out, for example, when we wrote:

A=5;

The 5 in the piece of code was a literal constants.

Literal constants can be divided in integer numerals, floating-point numerals, character,

strings and Boolean values.

Integer Numerals

1776

707

-273

They are numerical constants that identify decimal values. Notice that to express a numerical

constant we do not have to write quotes (") nor any special character. There is no doubt that

it is a constant: whenever we write 1776 in a program, we will be referring to the value

1776.

In addition to decimal numbers (those that all of us are used to use every day) C++ allows

the use as literal constants of octal numbers (base 8) and hexadecimal numbers (base 16). If

we want to express an octal number we have to precede it with a 0 (zero character). And in

order to express a hexadecimal number we have to precede it with the characters 0x (zero,

x). For example, the following literal constants are all equivalent to each other:

75 //decimal

0113 //octal

0x4b //hexadecimal

All of these represent the same number: 75 expressed as a base-10 numeral, octal numeral

and hexadecimal numeral, respectively.

Floating point numbers

They express numbers with decimals and/or exponents. They can include either a decimal

point, an e character (that express "by ten at the xth height", where x is an integer value that

follows the e character), or both a decimal point and an e character:

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3.14159 // 3.14159

6.02e23 // 6.02 x 10 ^ 23

1.6e-19 // 1.6 x 10^-19

3.0 // 3.0

Character and string literals

There also exist non-numerical constants, like:

'Z'

"Hello"

The 1st expression represent single character constant, and the 2

nd expression represent string

literals composed of several character. Notice that to represent a single character we enclose

it between quotes (') and to express a string (which generally consists of more than one

character) we enclose it between double quotes (").

When writing both single character and string literals, it is necessary to put the quotation

marks surrounding them to distinguish them from possible variable identifiers or reserved

keywords. Notice the difference between these two expressions:

x

'x'

x alone would refer to a variable whose identifier is x, whereas 'x' (enclosed within single quotation marks) would refer to the character constant 'x'.

Characters and string literals have certain peculiarities, like the escape codes. These are special characters that are difficult or impossible to express otherwise in the source code of program, like newline (\n) or tab (\t). All of them are preceded by a backslash (\). Here you have a list of some of such escape codes:

\n Newline \r Carriage return \t Tab \v Vertical tab \b Backspace \f Form feed (page feed) \a Alert (beep) \' Single quote (') \" Double quote (") \? Question mark (?) \\ Backslash (\)

For example:

'\n'

'\t'

"Left \t righr"

"one\ntwo\nthree"

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String literals can extend to more than a single line of code by putting a backslash sign (\) at

the end of each unfinished line.

"string expressed in \

two lines"

#define (directive)

Defines a macro

Syntax: #define <id1>[ ( <id2>, ... ) ] <token string>

The #define directive defines a macro.

Macros provide a mechanism for token replacement with or without a set of formal, function-

line parameters.

All subsequent instances of the identifier <id1> in the source text will be replaced by the text

defined by <token string>.

If <id1> is followed IMMEDIATELY by a "(", the identifiers following the "(" (<id2>, etc.)

are treated like parameters to a function instead of as part of <token string>.

All instances of <id2> in <token string> will be replaced with the actual text defined for

<id2> when <id1> is referenced in the source.

To continue the definitions on another line, end the current line with \

Example:

#define MAXINT 32767

#define ctrl(x) ((x) \

- 64) /* continued from preceding line */

It is legal but ill-advised to use Turbo C++ keywords as macro identifiers.

Example


#define x 5

int main()

{

Cout << "x:="<<x; //x=5

// ptintf("x=%d",x);

return 0;

}

In the above program, the value of x is fixed and can't be changed later

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Variables

As a programmer, you will frequently want your program to "remember" a value. For

example, if your program requests a value from the user, or if it calculates a value, you will

want to remember it somewhere so you can use it later. The way your program remembers

things is by using variables. Variables represent storage locations in the computer's memory.

For example:

int b;

This line says, "I want to create a space called b that is able to hold one integer value." A

variable has a name (in this case, b) and a type (in this case, int, an integer). You can store a

value in b by saying something like:

b = 5;

You can use the value in b by saying something like:

printf("%d", b); // cout << b

The output will be:

5

While writing:

printf("b"); // cout << "b"

The output will be:

b

and writing:

printf("b=%d",b); // cout << "b=" << b

The output will be:

b=5

To display a text line No.= with the value of b use:

Printf("No.=%d",b); // cout << "No.=" << b

The output will be:

No.=5

In C++, there are several standard types for variables:

Integer: int

Floating point: float

Character: char

An int is a 2-byte integer value. A float is a 4-byte floating point value. A char is a 1-byte

single character (like "a" or "A") or any other 8-bit quantity, when a character is stored in

memory, it is actually the numeric code is stored. A string is declared as an array of

characters.

There are a number of derivative types:

double (8-byte floating point value)

short (2-byte integer)

unsigned short or unsigned int (positive integers, no sign bit)

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Data Types Type Length Range

unsigned char 8 bits 0 to 255 char 8 bits -128 to 127 enum 16 bits -32,768 to 32,767 unsigned int 16 bits 0 to 65,535 short int 16 bits -32,768 to 32,767 int 16 bits -32,768 to 32,767 unsigned long 32 bits 0 to 4,294,967,295 long 32 bits -2,147,483,648 to 2,147,483,647 float 32 bits 3.4 * (10**-38) to 3.4 *

(10**+38) double 64 bits 1.7 * (10**-308) to 1.7 *

(10**+308) long double 80 bits 3.4 * (10**-4932) to 1.1 *

(10**+4932) void - valueless

Note: void data type specifies a valueless expression.

Examples:

char a='d';

int b=50;

float c=5.3;

Q) write a program to calculate the area of circle, radius=4.5 #include <iostream.h> #include <conio.h> #define pi 3.1415 int main() { float r=4.5,area; clrscr(); area=r*r*pi; cout << "Area of circle="<<area; getch(); }

Typedef You declare named, user-defined types in C++ with the typedef statement. The following example shows a type that appears often in C++ code:

If you do not like the word "float'' for real numbers, you can say:

typedef float real;

void main() { real r1,r2,r3; r1=5.2; }

You can place typedef statements anywhere in a C program as long as they come prior to their first use in the code.

sizeof (keyword) Returns the size, in bytes, of the given expression or type (as type size_t).

Syntax:

sizeof <expression>

sizeof ( <type> )

Example: cout << sizeof(char); // the output (in byte=8bits) will be 1

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Operators 3rd

week

Once we know of the existence of variables and constants, we can begin to operate with

them. For that purpose, C++ integrates operators, Unlike other languages whose operators are

mainly keywords, operators in C++ are mostly made of signs that are not part of the alphabet

but are available in all keyboards. This makes C++ code shorter and more international, since

it relies less on English words, but requires a little of learning effort in the beginning.

Arithmetic Operators

1- Plus and minus operators (+ and -)

Unary

In these unary + - expressions

+ cast-expression

- cast-expression

the cast-expression operand must be of arithmetic type.

Results

+ cast-expression: Value of the operand after any required integral promotions.

- cast-expression: Negative of the value of the operand after any required

integral promotions.

Example: y=-y;

Binary

Syntax:

add-expression + multiplicative-expression

add-expression - multiplicative-expression

Example:

z=x+y;

c=a-b;

2- Multiplicative operators ( * / % ) There are three multiplicative operators:

* (multiplication)

/ (division)

% (modulus or remainder)

Syntax:

multiplicative-expr * cast-expr

multiplicative-expr / cast-expr

multiplicative-expr % cast-expr

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Operands

* arithmetical type

/ arithmetical type

% integral type

The usual arithmetic conversions are made on the operands.

Results

(op1 * op2) Product of the two operands

(op1 / op2) Quotient of (op1 divided by op2)

(op1 % op2) Remainder of (op1 divided by op2)

For / and %, op2 must be nonzero; op2 = 0 results in an error. (You can't divide by zero.)

NOTE: Rounding is always toward zero. void main()

{

int a=5;

a=a%2;

printf("a=%d\n",a); //a=1 remainder of division a/2

// cout <<"a="<<a;

}

The / operator performs integer division if both operands are integers, and performs floating

point division otherwise. For example:

void main()

{

float a;

a=10/3;

printf("%f\n",a);

}

This code prints out a floating point value since a is declared as type float, but a will be 3.0

because the code performed an integer division.

Typecasting C++ allows you to perform type conversions on the fly. You do this especially often when

using pointers. Typecasting also occurs during the assignment operation for certain types. For

example, in the code above, the integer value was automatically converted to a float.

You do typecasting in C++ by placing the type name in parentheses and putting it in front of

the value you want to change. Thus, in the above code, replacing the line a=10/3; with

a=(float)10/3; produces 3.33333 as the result because 10 is converted to a floating point

value before the division, also you can say a=10.0/3;

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3- Increment/Decrement operators ( ++ and -- )

Increment operator ( ++ )

Syntax:

postfix-expression ++ (post increment)

++ unary-expression (pre increment)

The expression is called the operand; it must be of scalar type (arithmetic

or pointer types) and must be a modifiable lvalue.

Post increment operator

The value of the whole expression is the value of the postfix expression before the increment

is applied.

After the postfix expression is evaluated, the operand is incremented by 1.

Pre increment operator

The operand is incremented by 1 before the expression is evaluated; the value of the whole

expression is the incremented value of the operand.

The increment value is appropriate to the type of the operand.

Pointer types follow the rules for pointer arithmetic.

Notice the difference: Example 1:

b=3;

a=++b; // a contains 4, b contains 4

Example 2:

b=3;

a=b++; // a contains 3, b contains 4

In example 1, b is increased before its value is copied to a, while in example 2, the value of b

is copied to a then b is increased.

Decrement operator ( -- )

Syntax:

postfix-expression -- (post decrement)

-- unary-expression (pre decrement)

The decrement operator follows the same rules as the increment operator, except that the

operand is decremented by 1 after or before the whole expression is evaluated. Long Way Short Way another short Way

i=i+1; i++; ++i;

i=i-1; i--; --i;

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Bitwise operators 1- Bitwise complement operator ~ (tilde)

In the expression

~cast-expression

the cast-expression operand must be of integral type.

The result is the bitwise complement of the operand after any required integral promotions.

Each 0 bit in the operand is set to 1, and each 1 bit in the operand is set to 0.

2- Bitwise operators ( & ^ | ) Turbo C++ offers these bitwise operators:

& bitwise AND

^ bitwise exclusive OR

| bitwise inclusive OR

Syntax:

AND-expression & equality-expression

exclusive-OR-expr ^ AND-expression

inclusive-OR-expr | exclusive-OR-expression

In these expressions, both operands must be of integral type:

E1 & E2 E1 ^ E2 E1 | E2

The usual arithmetical conversions are performed on E1 and E2.

For the bitwise operators, each bit in the result is:

Bit value Results of

E1 E2 E1 & E2 E1 ^ E2 E1 | E2

0

0

1

1

0

1

0

1

0

0

0

1

0

1

1

0

0

1

1

1

3- Bitwise shift operators ( << >> )

Syntax:

shift-expression << additive-expression

shift-expression >> additive-expression

In the expressions E1 << E2 and E1 >> E2, the operands E1 and E2 must be of integral type.

The normal integral promotions are performed on E1 and E2, and the type of the result is the

type of the promoted E1.

If E2 is negative or is greater than or equal to the width in bits of E1, the operation is

undefined.

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Results

E1 << E2 Value of E1 left-shifted by E2 bit positions, zero-filled from the

right if necessary. Result=E1*2E2

E1 >> E2 Value of E1 right-shifted by E2 bit positions. Result=E1/2E2

In C++, these operators have been overloaded. void main()

{

int a=5;

a=a<<3;

printf("a=%d\n",a); //a=40 because a=5*23

a=a>>3;

printf("a=%d\n",a); //a=5 because a=a / 23

}

Assignment operators ( = etc.) There are 11 assignment operators in Turbo C++.

The = operator is the simple assignment operator; the other 10 are known as

compound assignment operators.

This is the complete set of assignment operators:

=

*= /= %= += -=

<<= >>= &= ^= |=

Syntax:

unary-expr assignment-op assignment-expr

In the expression E1 = E2

E1 must be a modifiable lvalue. The value of E2, after conversion to the type of E1, is stored

in the object designated by E1 (replacing E1's previous value).

The value of the assignment expression is the value of E1 after the assignment.

The compound assignments are op=, where op can be any one of the ten operator symbols

* / % + -

<< >> & ^ |

The expression

E1 op= E2

has the same effect as

E1 = E1 op E2

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except that the lvalue E1 is evaluated only once. For example, E1 += E2 is the same as E1 =

E1 + E2.

Long Way Short Way

i=i+3; i += 3;

i=i*j; i *= j;

i=i<<3; i<<=3;

i=i&3; i&=3;

Precedence of Operators

Operator precedence in C++ is also similar to that in most other languages. Division and

multiplication occur first, then addition and subtraction. The result of the calculation 5+3*4 is

17, not 32, because the * operator has higher precedence than + in C++. You can use

parentheses to change the normal precedence ordering: (5+3)*4 is 32. The 5+3 is evaluated

first because it is in parentheses. We'll get into precedence later -- it becomes somewhat

complicated in C++ once pointers are introduced.

In the following table of operator precedence, the Turbo C++ operators are divided into 16

categories.

The #1 category has the highest precedence; category #2 (Unary operators) takes second

precedence, and so on to the Comma operator, which has lowest precedence.

The operators within each category have equal precedence.

The Unary (category #2), Conditional (category #14), and Assignment (category #15)

operators associate right-to-left; all other operators associate left-to-right.

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# Category Operator What it is (or does)

1- Highest () Function call

[] Array subscript

-> C++ indirect component selector

:: C++ scope access/resolution

. C++ direct component selector

2- Unary ! Logical negation (NOT)

~ Bitwise (1's) complement

+ Unary plus

- Unary minus

++ Pre increment or post increment

-- Pre decrement or post decrement

& Address

* Indirection

sizeof (returns size of operand, in bytes)

new (dynamically allocates C++ storage)

delete (dynamically deallocates C++ storage)

3- Multiplicative * Multiply

/ Divide

% Remainder (modulus)

4- Member access .* C++ dereference

->* C++ dereference

5- Additive + Binary plus

- Binary minus

6- Shift << Shift left

>> Shift right

7- Relational < Less than

<= Less than or equal to

> Greater than

>= Greater than or equal to

8- Equality == Equal to

!= Not equal to

9- & Bitwise AND

10- ^ Bitwise XOR

11- | Bitwise OR

12- && Logical AND

13- || Logical OR

14- Conditional ?: (a ? x : y means "if a then x, else y")

15- Assignment = Simple assignment

*= Assign product

/= Assign quotient

%= Assign remainder (modulus)

+= Assign sum

-= Assign difference

&= Assign bitwise AND

^= Assign bitwise XOR

|= Assign bitwise OR

<<= Assign left shift

>>= Assign right shift

16- Comma , Evaluate

20

Input/ Output technique 4th

week

Until now, the example programs of previous sections provide very little interaction with the

user, if any at all. Using the standard input and output library, we will be able to interact with

the user by printing messages on the screen and getting the user's input from the keyboard.

C++ uses a convenient abstraction called streams to perform input and output operations in

sequential media such as the screen or the keyboard. A stream is an object where a program

can either insert or extract characters to/from it. We do not really need to care about many

specifications about the physical media associated with the stream – we only need to know it

will accept or provide characters sequentially.

The standard C++ library include the header file iostream, where the standard input and

output stream object are declared.

Standard output (cout)

By default, the standard output of a program is the screen, and the C++ stream object defined

to access it is cout.

cout is used in conjunction with the insertion operator, which is written as << (two "less than"

signs).

cout << "output sentence"; //prints output sentence on screen

cout << 120; // print number 120 on screen

cout << x; // prints the content of x on screen

The << operator inserts the data that follows it into the stream preceding it. In the example

above it inserted the constant string output sentence, the numerical constant 120 and variable

x into the standard output stream cout. Notice that the sentence in the first instruction is

enclosed between double quotes (") because it is a constant string of characters. Whenever we

want to use constant strings of characters we must enclose them between quotes (") so that

they can be clearly distinguished from variable names. For example, these two sentences

have very different results:

cout << "Hello"; // prints Hello

cout << Hello; // prints the content of Hello variable

The insertion operator (<<) may be used more than once in a single statement:

cout << " Hello," << "I am " << "a C++ statement";

This last statement would print the message Hello, I am a C++ statement on the screen. The

utility of repeating the insertion operator (<<) is demonstrated when we want to print out a

combination of variables and constants or more than one variable:

cout << "Hello, Iam "<< age<< " years old and my zipcode is "<< zipcode;

21

If we assume the age variable to contain the value 24 and the zipcode variable to contain

90064 the output of the previous statement would be:

Hello, I am 24 years old and my zipcode is 90064

It is important to notice that cout does not add a line break after its output unless we explicitly

indicate it, therefore, the following statements:

cout << "This is a sentence."

cout << "This is another sentence.";

Will be shown on the screen one following the other without any line break between them:

This is a sentence. This is another sentence.

Even though we had written them in two different insertions into cout. In order to perform a

line break on the output we must explicitly insert a new-line character into cout. In C++ a

new-line character can be specified as \n (backslash ,n):

cout << "First sentence.\n";

cout << "Second sentence.\nThird sentence.";

This produces the following output:

First sentence.

Second sentence.

Third sentence.

Additionally, to add a new-line, you may also use the endl manipulator. For example:

cout << "First sentence."<<endl;

cout << "Second sentence."<<endl;

Would print out:

First sentence.

Second sentence.

The endl manipulator produces a newline character, exactly as the insertion of '\n' does, but it

also has an additional behavior when it is used with buffered streams: the buffer is flushed.

Anyway, cout will be an unbuffered stream in most cases, so you can generally use both the

\n escape character and the endl manipulator in order to specify a new line without any

difference in its behavior.

22

Standard Input (cin)

The standard input device is usually the keyboard. Handing the standard input in C++ is done

by applying the overloaded operator of extraction (>>) on the cin stream. The operator must

be followed by the variable that will store the data that is going to be extracted from the

stream. For example:

int age;

cin >> age;

The first statement declares a variable of type int called age, and the second one waits for an

input from cim (the keyboard) in order to store it in this integer variable.

cin can only process the input from the keyboard once the return key has been pressed.

Therefore, even if you request a single character, the extraction from cin will not process the

input until the user presses return after the character has been introduced.

You must always consider the type of the variable that you are using as container with cin

extractions. If you request an integer you will get an integer, if you request a character you

will get a character and if you request a string of character you will get a string of character.

// I/O example


int main()

{

int i;

cout << "Please enter an integer value: ";

cin >> i;

cout << "The value you entered is " << i;

cout << " and its double is " << i*2 << ".\n";

return 0;

}

This produces the following output:

Please enter an integer value: 702

The value you entered is 702 and its double is 1404.

The user of a program may be one of the factors that generate errors even in the simplest

programs that use cin (like the one we have just seen). Since if you request an integer value

and the user introduce a name (which generally is a string of characters), the result may cause

your program to misoperate since it is not what we were expecting from the user. So when

23

you use the data input provided by cin extractions you will have to trust that the user of your

program will be cooperative and that he/she will not introduce his/her name or something

similar when an integer value is requested. A little ahead, when we see the string stream class

we will see a possible solution for the errors that can be caused by this type of user input.

You can also use cin to request more than one datum input from the user:

cin >> a >> b;

Is equivalent to:

cin >> a;

cin >> b;

Q) write a program to calculate the area of circle


#include <conio.h>

#define pi 3.1415

int main()

{

float r,area;

clrscr();

cout << "radius=";

cin >> r;

area=r*r*pi;

cout << "Area of circle="<<area;

getch();

}

Q) exchange two numbers

#include <iostream.h> #include <conio.h> int main() { int x, y,z; clrscr(); cout <<"x="; cin >>x; cout <<"y="; cin >>y; z=x; x=y; y=z; cout <<"New x="<<x<<"\n"; cout <<"New y="<<y; getch(); }

24

Printf

The printf statement allows you to send output to standard out. For us, standard out is

generally the screen (although you can redirect standard out into a text file or another

command).

Let's look at some variations to understand printf completely. Here is the simplest printf

statement:

printf("Hello");

This call to printf has a format string that tells printf to send the word "Hello" to standard out.

Contrast it with this:

printf("Hello\n");

The difference between the two is that the second version sends the word "Hello" followed

by a carriage return to standard out.

The following line shows how to output the value of a variable using printf.

printf("%d", b);

The %d is a placeholder that will be replaced by the value of the variable b when the printf

statement is executed. Often, you will want to embed the value within some other words. One

way to accomplish that is like this:

printf("The temperature is ");

printf("%d", b);

printf(" degrees\n");

An easier way is to say this:

printf("The temperature is %d degrees\n", b);

You can also use multiple %d placeholders in one printf statement:

printf("%d + %d = %d\n", a, b, c);

In the printf statement, it is extremely important that the number of operators in the format

string corresponds exactly with the number and type of the variables following it. For

example, if the format string contains three %d operators, then it must be followed by exactly

three parameters and they must have the same types in the same order as those specified by

the operators.

You can print all of the normal C++ types with printf by using different placeholders:

int (integer values) uses %d

float (floating point values) uses %f

char (single character values) uses %c

character strings (arrays of characters, discussed later) use %s

25

Here is a program that will help you learn more about printf:

#include <stdio.h> int main() { int a, b, c; a = 5; b = 7; c = a + b; printf("%d + %d = %d\n", a, b, c); return 0; }

The output will be:

5 + 7 = 12.

Here is an explanation of the different lines in this program:

The line int a, b, c; declares three integer variables named a, b and c. Integer

variables hold whole numbers.

The next line initializes the variable named a to the value 5.

The next line sets b to 7.

The next line adds a and b and "assigns" the result to c.

The computer adds the value in a (5) to the value in b (7) to form the result 12, and

then places that new value (12) into the variable c. The variable c is assigned the

value 12. For this reason, the = in this line is called "the assignment operator."

The printf statement then prints the line "5 + 7 = 12." The %d placeholders in the

printf statement act as placeholders for values. There are three %d placeholders, and

at the end of the printf line there are the three variable names: a, b and c. C++

matches up the first %d with a and substitutes 5 there. It matches the second %d with

b and substitutes 7. It matches the third %d with c and substitutes 12. Then it prints

the completed line to the screen: 5 + 7 = 12. The +, the = and the spacing are a part of

the format line and get embedded automatically between the %d operators as

specified by the programmer.

Example: difference between cout and printf


#include <stdio.h>

#include <conio.h>

int main()

{

char a='C';

clrscr();

printf("character: %c ASCII Code: %d hexa code:%x\na",a,a,a);

cout << a; //C

getch();

}

26

Scanf

The scanf function allows you to accept input from standard in, which for us is generally

the keyboard. The scanf function can do a lot of different things, but it is generally unreliable

unless used in the simplest ways. It is unreliable because it does not handle human errors very

well. But for simple programs it is good enough and easy-to-use.

The simplest application of scanf looks like this:

scanf("%d", &b);

The program will read in an integer value that the user enters on the keyboard (%d is for

integers, as is printf, so b must be declared as an int) and place that value into b.

The scanf function uses the same placeholders as printf:

int uses %d

float uses %f

char uses %c

character strings (discussed later) use %s

You MUST put & in front of the variable used in scanf. The reason why will become clear

once you learn about pointers. It is easy to forget the & sign, and when you forget it your

program will almost always crash when you run it.

In general, it is best to use scanf as shown here -- to read a single value from the keyboard.

Use multiple calls to scanf to read multiple values.

Modify the previous program to accept input values:

#include <stdio.h> int main() { int a, b, c; printf("Enter the first value:"); scanf("%d", &a); printf("Enter the second value:"); scanf("%d", &b); c = a + b; printf("%d + %d = %d\n", a, b, c); return 0; }

Try deleting or adding random characters or words in one of the previous programs and

watch how the compiler reacts to these errors.

For example, delete the b variable in the first line of the above program and see what the

compiler does when you forget to declare a variable. Delete a semicolon and see what

happens. Leave out one of the braces. Remove one of the parentheses next to the main

function. Make each error by itself and then run the program through the compiler to see

what happens. By simulating errors like these, you can learn about different compiler errors,

and that will make your typos easier to find when you make them for real.

27

C++ Errors to Avoid

Using the wrong character case - Case matters in C++, so you cannot type Printf or

PRINTF. It must be printf.

Forgetting to use the & in scanf

Too many or too few parameters following the format statement in printf or scanf

Forgetting to declare a variable name before using it

Q) write a program to read 3 values of character, integer, and float in one line

#include <stdio.h>

#include <conio.h>

int main(void)

{

char a; int b; float c;

clrscr();

printf("Enter 3 values: character integer float\n");

printf("---------------------------------------\n");

scanf("%c%d%f",&a,&b,&c);

printf("character:%c integer:%d float:%f",a,b,c);

getch();

return 0;

}

Q) write a program to calculate the area of circle

#include <stdio.h>

#include <conio.h>

#define pi 3.1415

int main()

{

float r,area;

clrscr();

printf("radius="); scanf("%f",&r); area=r*r*pi;

printf("Area of circle=%4.3f",area);

getch();

}

28

Relational operators ( < > <= and >= ) 5th

week

The relational operators are used to compare relative values.

Syntax:

relational-expression < shift-expression

relational-expression > shift-expression

relational-expression <= shift-expression

relational-expression >= shift-expression

E1 < E2 Gives 1 (true) if the value of E1 is less than value of E2; otherwise, the result is 0

(false)

E1 <= E2 Gives 1 (true) if the value of E1 is less than or equal to the value of E2;

otherwise, the result is 0 (false).

E1 > E2 Gives 1 (true) if the value of E1 is greater than the value of E2; otherwise, the

result is 0 (false)

E1 >= E2 Gives 1 (true) if the value of E1is greater than or equal to the value of E2;

otherwise, the result is 0 (false).

Equality operators ( == and != ) The operators == and != are used to test for equality or inequality between arithmetic

or pointer values, following rules similar to those for the relational operators.

The equality operators have lower precedence than the relational operators, however,

and you can also compare certain pointer types not allowed with relational operations.

If E1 == E2 gives 1 (true), then either E1 and E2 point to the same function, or they are both

null.

The expression E1 != E2 follows the same rules, except that the result is 1 (true) if the

operands are unequal, and 0 (false) if the operands are equal.

Conditional operator ( ? : ) The conditional operator ?: is a ternary operator.

Syntax:

condition ? result1 : result2

If condition is true the expression will return result1, if it is not it will return result2.

In the expression E1 ? E2 : E3

E1 is evaluated first. If its value is nonzero (true), then E2 is evaluated and E3 is ignored. If

E1 evaluates to zero (false), then E3 is evaluated and E2 is ignored.

The result of E1 ? E2 : E3 will be the value of whichever of E2 and E3 is evaluated.

29


#include <conio.h>

int main()

{

int i,j,k;

clrscr();

cout << "i:=";

cin >> i;

cout << "j:=";

cin >> j;

k=(i==j) ? 2:5;

cout<<"k:="<<k;

cout << "\n\nHit any key to continue";

getch();

return 0;

}

In the previous program, when the value of i is equal to the value of j then k becomes

equal 2, otherwise k is equal to 5

Comma punctuator and operator ( , ) The comma separates the elements of a function argument list.

The comma is also used as an operator in comma expressions. Mixing the two uses of comma

is legal, but you must use parentheses to distinguish them.

Syntax:

expression , assignment-expression

The left operand E1 is evaluated as a void expression, then E2 is evaluated to give the result

and type of the comma expression. By recursion, the expression

E1, E2, ..., En

results in the left-to-right evaluation of each Ei, with the value and type of En giving the

result of the whole expression.

Example1:

A=(b=3,b+2);

Would first assign the value 3 to b, and then assign b+2 to variable a. So, at the end, variable

a would contain the value 5 while variable b would contain value 3. Example2:

To avoid ambiguity with the commas used in function argument and initialize

lists, parentheses must be used. For example,

func(i, (j = 1, j + 4), k);

calls func with three arguments, not four. The arguments are i, 5, and k.

30

The if statement (keyword) 6th

week

The first type of branching statement we will look at is the if statement. The if statement

can cause other statements to execute only under certain conditions. An if statement has the

form:

if ( <expression> ) <statement1>;

If <expression> is non-zero when evaluated, <statement1> is executed.

Example:

if (count < 50) count++;

Here is a simple C++ program demonstrating an if statement:

#include <stdio.h> int main() { int b; printf("Enter a value:"); scanf("%d", &b); if (b < 0) printf("The value is negative\n"); return 0; }

This program accepts a number from the user. It then tests the number using an if statement

to see if it is less than 0. If it is, the program prints a message "The value is negative".

Otherwise, the program is silent. The (b < 0) portion of the program is the Boolean

expression. C++ evaluates this expression to decide whether or not to print the message. If

the Boolean expression evaluates to True, then C++ executes the single line immediately

following the if statement (or a block of lines within braces immediately following the if

statement). If the Boolean expression is False, then C++ skips the line or block of lines

immediately following the if statement.

If (condition)

{

Statement1;

Statement2;

.

.

Statementn;

}

http://www.howstuffworks.com/boolean.htm

http://www.howstuffworks.com/boolean.htm

31

Example: to update the previous program, if the value of b is negative then add 50 to b then

print the new value of b. The program will be:

#include <stdio.h>

int main()

{

int b;

printf("Enter a value:");

scanf("%d", &b);

if (b < 0)

{

b+=50;

printf("b=%d\n",b);

}

return 0;

}

32

Q) Write a program to check if the no. is positive, then print positive number


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if (x > 0)

cout << " --- Positive Number ---\n";

cout << "Hit any key to continue";

getch ;)(

return 0;

}

Q) Write a program to check if the student pass in English language


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Degree:=";

cin >> x;

if (x >=50)

cout << " --- Pass ---\n";


getch ;)(

return 0;

}

Q) Write a program to check the no., if it is even then print even number


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if ((x % 2)==0) // if (!(x % 2))

cout << " --- Even Number ---\n";


getch ;)(

return 0;

}

33

Q) Write a program to check if the no. accept division by 5 without remainder, then

print that


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if ((x % 5)==0) // if (!(x % 5))

cout << " --- Number accept division by 5 ---\n";


getch)(

return 0;

}

Q) Write a program to solve the following equation

y=x+1-y when x>=20


#include <conio.h>

int main()

{

int x,y;

clrscr();

cout << "x:=";

cin >> x;

cout << "y:=";

cin >> y;

if (x >=20)

{

y=x+1-y; //also valid y=++x-y; invalid y=x++-y; (error)

cout << " y:="<<y<<"\n";

}


getch();

return 0;

}

34

The If –else statement

if ( <expression> ) <statement1>;

else <statement2>;

If <expression> is non-zero when evaluated, <statement1> is executed. Otherwise

<statement2> is executed if the expression is 0.

An optional else can follow an if statement, but no statements can come between an if

statement and an else.

Example:

if (x < y)

z = x;

else

z = y;

The #if and #else preprocessor statements (directives) look similar to the if and else

statements, but have very different effects.

They control which source file lines are compiled and which are ignored.

In an if statement, condition is a value or an expression that is used to determine which

code block is executed, and the curly braces act as "begin" and "end" markers.

if (condition)

{

// code to execute if condition is true

}

else

{

// code to execute if condition is false

}

Here is a full C++ program as an example:

#include <iostream.h> //include this file for cout

int main() {

// define two integers

int x = 3;

int y = 4;

//print out a message telling which is bigger

if (x > y)

cout << "x is bigger than y" << endl;

else

cout << "x is not bigger than y" << endl;

return 0;

}

35

In this case condition is equal to "(x > y)" which is equal to "(3 > 4)" which is a false

statement. So the code within the else clause will be executed. The output of this program

will be:

x is not bigger than y

If instead the value for x was 6 and the value for y was 2, then condition would be "(6 > 2)"

which is a true statement and the output of the program would be: x is bigger than y

Q) Write a program to check if the no. is positive or not positive


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if (x > 0)

cout << " --- Positive Number ---\n";

else

cout << " --- The number is not positive ---\n";


getch ;)(

return 0;

}

Q) Write a program to check if the student pass in English language or not


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Degree:=";

cin >> x;

if (x >=50)

cout << " --- Pass ---\n";

else

cout << " --- Fail ---\n";


getch ;)(

return 0;

}

36

Q) Write a program to check if the NO. is even or odd


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if ((x % 2)==0) // if (!(x % 2))

cout << " --- Even Number ---\n";

else

cout << " --- Odd Number ---\n";


getch ;)(

return 0;

}

Q) Write a program to check if the no. accept division by 5 without remainder, then

print that


#include <conio.h>

int main)(

{

int x;

clrscr)(;

cout << "Number:=";

cin >> x;

if ((x % 5)==0) // if (!(x % 5))

cout << " --- Number accept division by 5 without remainder ---\n";

else

cout << " --- Number don't accept division by 5 without remainder ---

\n";


getch)(

return 0;

}

37

Q) Write a program to solve the following equations

Y=x+1-y when x>=20

Y=(x-1)*y when x<20


#include <conio.h>

int main()

{

int x,y;

clrscr();

cout << "x:=";

cin >> x;

cout << "y:=";

cin >> y;

if (x >=20)

{

y=++x-y; // if we don't need to change x then y=x+1-y

cout << " y:="<<y<<"\n";

}

else

{

y=--x*y;// if we don't need to change x then y=(x-1)*y

cout << " y:="<<y<<"\n";

}


getch();

return 0;

}

Note: It is better to write the following program rather the previous

one


#include <conio.h>

int main()

{

int x,y;

clrscr();

cout << "x:=";

cin >> x;

cout << "y:=";

cin >> y;

if (x >=20)

y=++x-y;

else

y=--x*y;

cout << " y:="<<y<<"\n";//because in both cases, y is the output


getch();

return 0;

}

38

If/else if/ else statement 7th

week

The (if/else if) statement is a chain of if statements. They perform

their tests, one after the other, until one of them is found to be

true.

This construction is like a chain of (if/else) statements. The else

part of one statement is linked to the if part of another. When put

together this way, the chain of if/else becomes one long statement.

if (condition1)

{

// code to execute if condition1 is true

}

else if (condition2)

{

//code to execute if condition1=false but condition2=true

}

Else

{

//code to execute if both condition1 and condition2=false

}

Or it can be written as:

if (condition1)

{

// code to execute if condition1 is true

}

Else

{

if (condition2)

{

//code to execute if condition1=false but condition2=true

}

Else

{

//code to execute if both condition1 and condition2=false

}

}

Here's slightly more complex example:

#include <stdio.h> int main() { int b; printf("Enter a value:"); scanf("%d", &b); if (b < 0) printf("The value is negative\n"); else if (b == 0) printf("The value is zero\n"); else printf("The value is positive\n"); return 0; }

39


y=x+1-y when x>20

y=(x-1)*y when x<20

y=x when x=20

#include <iostream.h> #include <conio.h> int main() { int x,y; clrscr(); cout << "x:="; cin >> x; cout << "y:="; cin >> y; if (x >20) y=++x-y; // valid y=x+1-y; else if (x<20) y=--x*y; // valid y=(x-1)*y else y=x; cout << " y:="<<y<<"\n"; cout << "Hit any key to continue"; getch(); return 0; }


a=a/10 when a>b

b=a/3 when a<b

a=a*b when a=b

#include <iostream.h> #include <conio.h> int main() { float a,b; clrscr(); cout << "a:="; cin >> a; cout << "b:="; cin >> b; if (a >b) { a/=10.0; cout << " a:="<<a<<"\n"; } else if (a<b) { b=a/3.0; cout << " b:="<<b<<"\n"; } else { a=a*b; cout << " a:="<<a<<"\n"; } cout << "Hit any key to continue"; getch(); return 0; }

40

Nested if 8th

week

Nested if used when we need to test condition after another condition happened. It has the form:

if (condition1)

{

If (condition2)

{

}

Else

{

}

}

Else

{

}

Q) Write a program to check if the no. is even and accept division by 5 without

remainder


#include <conio.h>

int main()

{

int a;

clrscr();

cout << "Number:=";

cin >> a;

if ((a % 2)==0)

if ((a % 5)==0)

cout << " even number accept division by 5\n";


getch();

return 0;

}

Q) Write a program to check if the no. is odd and negative


#include <conio.h>

int main()

{

int a;

clrscr();

41

cout << "Number:=";

cin >> a;

if ((a % 2)!=0)

if (a<0)

cout << "--- negative odd number ---\n";


getch();

return 0;

}


When a>=5

b=a-1 when b>=20

b=a+1 when b<20

When a<5

b=a*5 when b>=20

b=a/5 when b<20


#include <conio.h>

int main()

{

float a,b;

clrscr();

cout << "a:=";

cin >> a;

cout << "b:=";

cin >> b;

if (a >=5)

if (b>=20)

b=a-1;

else

b=a+1;

else

if (b>=20)

b=a*5;

else

b=a/5.0;

cout << " b:="<<b<<"\n";


getch();

return 0;

}

42

Logical operator

1- Logical operator (&&,||) Turbo C++ offers these logical operators:

&& logical AND

|| logical OR

Syntax:

logical-AND-expr && inclusive-OR-expression

logical-OR-expr || logical-AND-expression

In these expressions, both operands must be of scalar type.

E1 && E2 E1 || E2

The usual arithmetical conversions are performed on E1 and E2.

Unlike the bitwise operators, && and || guarantee left-to-right evaluation.

E1 is evaluated first; if E1 is zero, E1 && E2 gives 0 (false), and E2 is not evaluated.

With E1 || E2, if E1 is nonzero, E1 || E2 gives 1 (true), and E2 is not evaluated.

2- Logical negation operator !

In the expression

! cast-expression

the cast-expression operand must be of scalar type.

The result is of type int and is the logical negation of the operand:

0 if the operand is nonzero

1 if the operand is 0

The expression !E is equivalent to (0 == E).

If with logical operator

Here is a more complicated Boolean expression:

if ((x==y) && (j>k))

z=1;

else

q=10;

This statement says, "If the value in variable x equals the value in variable y, and if the value

in variable j is greater than the value in variable k, then set the variable z to 1, otherwise set

the variable q to 10." You will use if statements like this throughout your C++ programs to

43

make decisions. In general, most of the decisions you make will be simple ones like the first

example; but on occasion, things get more complicated.

Notice that C++ uses = = to test for equality, while it uses = to assign a value to a variable.

The && in C++ represents a Boolean AND operation.

Boolean expressions evaluate to integers in C++, and integers can be used inside of

Boolean expressions. The integer value 0 in C++ is False, while any other integer value is

True. The following is legal in C++:

#include <stdio.h>

int main()

{

int a;

printf("Enter a number:");

scanf("%d", &a);

if (a)

{

printf("The value is True\n");

}

return 0;

}

If a is anything other than 0, the printf statement gets executed.

In C++, a statement like if (a=b) means, "Assign b to a, and then test a for its Boolean

value." So if a becomes 0, the if statement is False; otherwise, it is True. The value of a

changes in the process. This is not the intended behavior if you meant to type = = (although

this feature is useful when used correctly), so be careful with your = and = = usage.

Q) Write a program to check if the no. is even and accept division by 5 without

remainder


#include <conio.h>

int main()

{

int a;

clrscr();

cout << "Number:=";

cin >> a;

if ((!(a % 2)) && (!(a % 5)))

cout << " even number accept division by 5\n";


getch();

return 0;

}

http://www.howstuffworks.com/boolean1.htm

44

Q) Write a program to check if the no. is odd and negative


#include <conio.h>

int main()

{

int a;

clrscr();

cout << "Number:=";

cin >> a;

if ((a % 2) && (a<0))

cout << "--- negative odd number ---\n";


getch();

return 0;

}


When a>=5

b=a-1 when b>=20

b=a+1 when b<20

When a<5

b=a*5 when b>=20

b=a/5 when b<20


#include <conio.h>

int main()

{

float a,b;

clrscr();

cout << "a:=";

cin >> a;

cout << "b:=";

cin >> b;

if ((a >=5) && (b>=20))

b=a-1;

else if ((a >=5) && (b<20))

b=a+1;

else if ((a<5) && (b>=20))

b=a*5;

else if ((a<5) && (b<20))

b=a/5.0;

cout << " b:="<<b<<"\n";


getch();

return 0;

}

45

Q) Write a program to check the degree of the student


#include <conio.h>

int main()

{

int a;

clrscr();

cout << "Degree:=";

cin >> a;

if (a >=90)

cout << " Excellent\n";

else if ((a >=80) && (a<90))

cout << " Very good\n";

else if ((a >=70) && (a<80))

cout << " Good\n";

else if ((a >=60) && (a<70))

cout << " Medium\n";

else if ((a >=50) && (a<60))

cout << " Accepted\n";

else

cout << " Fail\n";


getch();

return 0;

}

46

The switch statement 9th

week

The next branching statement is called a switch statement. A switch statement is used in

place of many if statements.

If you want to test whether a variable takes one of a series of values, it's easier to use a

switch statement than an if statement.

switch (<variable>) {

case <value 1>:

<one or more statements>

break;

case <value 2>:


break;

default:


break;

} //end switch

switch, case, and default (keywords)

Branches control

Syntax:

- switch ( <expression> ) <statement>

- case <constant expression> :

- default :

switch

Causes control to branch to one of a list of possible statements in the block defined by

<statement>.

The branched-to statement is determined by evaluating <expression>, which must return an

integral type.

case

The list of possible branch points within <statement> is determined by preceding sub

statements with

case <constant expression> :

where <constant expression> must be an int and must be unique.

47

Once a value is computed for <expression>, the list of possible <constant expression> values

determined from all case statements is searched for a match.

If a match is found, execution continues after the matching case statement and continues until

a break statement is encountered or the end of <statement> is reached.

default

If a match is not found and the "default :" statement prefix is found within <statement>,

execution continues at this point.

Otherwise, <statement> is skipped entirely.

Example:

switch (operand) {

case MULTIPLY: x *= y; break;

case DIVIDE: x /= y; break;

case ADD: x += y; break;

case SUBTRACT: x -= y; break;

case INCREMENT2: x++;

case INCREMENT1: x++; break;

case EXPONENT:

case ROOT:

case MOD: printf("Not done\n"); break;

default: printf("Bug!\n");

exit(1);

}

Let's consider the following case: Joel is writing a program that figures interest on money

that is held in a bank. The amount of interest that money earns in this bank depends on

which type of account the money is in. There are 6 different types of accounts and they

earn interest as follows:

account type interest earned

personal financial 2.3%

personal homeowner 2.6%

personal gold 2.9%

small business 3.3%

big business 3.5%

gold business 3.8%

One way for Joel to write this program is as follows: (assuming also that Joel has

assigned numbers to the account types starting with personal financial and ending with

gold business.)

48

// declare a variable to keep track of the interest

float interest = 0.0;

// decide which interest rate to use.

if (account_type == 1){

interest = 2.3;

}

else {

if (account_type == 2) {

interest = 2.6;

}

else {


interest = 2.9;

}

else {


interest = 3.3;

}

else {


interest = 3.5;

}

else {

// account type must be 6

interest = 3.8;

}

}

}

}

}

That code is hard to read and hard to understand. There is an easier way to write this,

using the switch statement. The preceding chunk of code could be written as follows:

switch (account_value){

case 1:

interest = 2.3;

break;

case 2:

interest = 2.6;

break;

case 3:

interest = 2.9;

break;

case 4:

interest = 3.3;

break;

case 5:

interest = 3.5;

break;

case 6:

interest = 3.8;

break;

default:

interest = 0.0;

}

The switch statement allows a programmer to compound a group of if statements,

provided that the condition being tested is an integer.

49

The default clause is optional, but it is good programming practice to use it. The default

clause is executed if none of the other clauses have been executed. For example, if my

code looked like:

switch (place) {

case 1:

cout << "we're first" << endl;

break;

case 2:

cout << "we're second" << endl;

break;

default:

cout << "we're not first or second" << endl;

}

This switch statement will write "we're first" if the variable place is equal to 1, it will

write "we're second" if place is equal to 2, and will write "we're not first or second" if

place is any other value.

The break keyword means "jump out of the switch statement, and do not execute any

more code." To show how this works, examine the following piece of code:

int value = 0;

switch(input){

case 1:

value+=4;

case 2:

value+=3;

case 3:

value+=2;

default:

value++;

}

If input is 1 then 4 will be added to value. Since there is no break statement, the program

will go on to the next line of code which adds 3, then the line of code that adds 2, and

then the line of code that adds 1. So value will be set to 10!

The code that was intended was probably:

int value = 0;

switch(input){

case 1:

value+=4;

break;

case 2:

value+=3;

break;

case 3:

value+=2;

break;

default:

value++;

}

50

This feature of switch statements can sometimes be used to a programmers' advantage. In

the example with the different types of bank accounts, say that the interest earned was a

follows:

account type interest earned

personal financial 2.3%

personal homeowner 2.6%

personal gold 2.9%

small business 2.6%

big business 2.9%

gold business 3.0%

Now, the code for this could be written as:

switch (account_value){

case 1:

interest = 2.3;

break;

case 2:

case 4:

interest = 2.6;

break;

case 3:

case 5:

interest = 2.9;

break;

case 6:

interest = 3.0;

break;

default:

interest = 0.0;

}

Q) Write a program to calculate the area or circumference of rectangle using menu #include <iostream.h>

#include <conio.h>

int main()

{

int a;

int l,w,r;

clrscr();

cout << "*********************************\n";

cout << "* 1: Area of rectangle *\n";

cout << "* 2: Circumference of rectangle *\n";

cout << "*********************************\n\n";

cout << "Length:=";

cin >> l;

cout << "Width:=";

cin >> w;

cout << "\nChoice:=";

cin >> a;

switch (a)

51

{

case 1:

r=l*w;

cout << "\n Area of rectangle:="<<r;

break;

case 2:

r=(l+w)*2;

cout << "\n Circumference of rectangle:="<<r;

break;

}


getch();

return 0;

}

* You can write the same previous program depending on character


#include <conio.h>

#include <ctype.h>

int main()

{

char a;

int l,w,r;

clrscr();

cout << "*********************************\n";

cout << "* A: Area of rectangle *\n";

cout << "* C: Circumference of rectangle *\n";

cout << "*********************************\n\n";

cout << "Length:=";

cin >> l;

cout << "Width:=";

cin >> w;

cout << "\nChoice:=";

cin >> a;

switch (toupper(a)) // to convert the character to upper case

{

case 'A':

r=l*w;

cout << "\n Area of rectangle:="<<r;

break;

case 'C':

r=(l+w)*2;

cout << "\n Circumference of rectangle:="<<r;

break;

default:

cout << "\n Error Choice";

}


getch();

return 0;

}

52

The iteration (looping) statement : (if with counter) 10th

week

Looping is the repetition of a statement or block of statements in a program.

goto (keyword)

Transfers control

Syntax: goto <identifier> ;

Control is unconditionally transferred to the location of a local label specified by

<identifier>.

Example:

Again:

;

.

.

goto Again;

NOTE: Labels must be followed by a statement (;).

Q) Write a program to print number from 1..5 in ascending order


#include <conio.h>

int main()

{

int i;

clrscr();

i=1;

lab:

cout <<i<<" ";

i++; // equal to ++i;

if (i<=5) goto lab;

cout << "\n\nHit any key to continue"; //i=6

getch();

return 0;

}

The program can be written in another way


#include <conio.h>

int main()

{

int i;

clrscr();

i=1;

lab:

cout <<i<<" ";

if (++i<=5) goto lab; // error to say i++

cout << "\n\nHit any key to continue"; //i=6

getch();

return 0;

}

53

Q) Write a program to print number from 5..1 in descending order

#include <iostream.h> #include <conio.h> int main() { int i; clrscr(); i=5; lab: cout <<i<<" "; if (--i>=1) goto lab; // error to say i-- cout << "\n\nHit any key to continue"; //i=0 getch(); return 0; }

Q) Write a program to find the factorial of any number #include <iostream.h> #include <conio.h> int main() { int n,i; long int f; clrscr(); cout << "Number:="; cin >> n; if (n>=1) { i=1; f=1; lab: f=f*i; if (++i<=n) goto lab; cout <<"Factorial number:="<<f; } cout << "\n\nHit any key to continue"; getch(); return 0; }

Q) Write a program to find the factorial of 3 different numbers #include <iostream.h> #include <conio.h> int main() { int n,i,k; long int f; clrscr(); k=1; lfno: cout << "Number:="; cin >> n; if (n>=1) { i=1; f=1; lab: f=f*i; if (++i<=n) goto lab; cout <<"Factorial number:="<<f<<"\n\n"; } if (++k<=3) goto lfno; cout << "\n\nHit any key to continue"; getch(); return 0; }

54

Q) Write a program to solve the following equation:

𝒔𝒖𝒎 = 𝟒 +𝟕

𝟐+

𝟓

𝟑+

𝟑

𝟒

#include <iostream.h> #include <conio.h> int main() { int i=2,j=7; float sum=4.0; clrscr(); lnext: cout <<"i="<<i<<" j="<<j<<"\n"; // for test sum=sum+(float )j/i; j=j-2; if (++i<=4) goto lnext; cout<<"sum="<<sum; cout << "\n\nHit any key to continue"; getch(); return 0; }


𝒔𝒖𝒎 = 𝟒 −𝟕

𝟐+

𝟓

𝟑−

𝟑

𝟒

#include <iostream.h> #include <conio.h> int main() { int i=2,j=7,s=-1; float sum=4.0; clrscr(); lnext: cout <<"i="<<i<<" j="<<j<<" s="<<s<<"\n"; // for test sum=sum+s*(float )j/i; j=j-2; s=-s; if (++i<=4) goto lnext; cout<<"sum="<<sum; cout << "\n\nHit any key to continue"; getch(); return 0;

}


𝒔𝒖𝒎 = 𝟑 +𝟐!

𝟑+

𝟓!

𝟗−

𝟖!

𝟐𝟕

#include <iostream.h> #include <conio.h> int main() { int j=3,n=2,i; long int f; float sum=3.0; clrscr(); lfno: i=1; f=1; cout <<"n="<<n<<" j="<<j<<"\n"; lab: f=f*i; if (++i<=n) goto lab; cout<<"Number:="<<n<<" Factorial number:="<<f<<"\n\n";//test sum=sum+(float )f/j; j*=3; n+=3; if (n<=8) goto lfno; cout <<"sum:="<<sum; cout << "\n\nHit any key to continue"; getch(); return 0; }

55

For (keyword) 11th

week

For loop

Syntax: for ( [<expr1>] ; [<expr2>] ; [<expr3>] ) <statement>

<statement> is executed repeatedly UNTIL the value of <expr2> is 0.

BEFORE the first iteration, <expr1> is evaluated. This is usually used to initialize variables

for the loop.

AFTER each iteration of the loop, <expr3> is evaluated. This is usually used to increment a

loop counter.

In C++, <expr1> can be an expression or a declaration.

The scope of any declared identifier extends to the end of the control statement only.

All the expressions are optional. If <expr2> is left out, it is assumed to be 1.

The following statement is used for infinite loop: for ( ;;)



#include <conio.h>

int main()

{

clrscr();

for (int i=1;i<=5;++i)

cout <<i<<" ";

//out the loop i=6


getch();

return 0;

}



#include <conio.h>

int main()

{

clrscr();

for (int i=5;i>=1;--i)

cout <<i<<" ";

//out the loop i=0


getch();

return 0;

}

56

Q) Write a program to find the factorial of any number #include <iostream.h>

#include <conio.h>

int main()

{

int n;

long int f;

clrscr();

cout << "Number:=";

cin >> n;

if (n>=1)

{

for (int i=1,f=1;i<=n;++i)

f=f*i;

cout <<"Factorial number:="<<f;

}


getch();

return 0;

}

Q) Write a program to find the factorial of 3 different numbers #include <iostream.h>

#include <conio.h>

int main()

{

int n;

long int f;

clrscr();

for (int j=1;j<=3;++j)

{

cout << "Number:=";

cin >> n;

if (n>=1)

{

for (int i=1,f=1;i<=n;++i)

f=f*i;

cout <<"Factorial number:="<<f<<"\n\n";

}

}


getch();

return 0;

}


𝒔𝒖𝒎 = 𝟒 +𝟕

𝟐+

𝟓

𝟑+

𝟑

𝟒


#include <conio.h>

int main()

{

float sum=4.0;

clrscr();

for (int i=2,j=7;i<=4;++i,j=j-2)

{

cout <<"i="<<i<<" j="<<j<<"\n"; // for test

57

sum=sum+(float )j/i;

}

cout<<"sum="<<sum;


getch();

return 0;

}


𝒔𝒖𝒎 = 𝟒 −𝟕

𝟐+

𝟓

𝟑−

𝟑

𝟒


#include <conio.h>

int main()

{

float sum=4.0;

clrscr();

for (int i=2,j=7,s=-1;i<=4;++i,j=j-2,s=-s)

{

cout <<"i="<<i<<" j="<<j<<" s="<<s<<"\n"; // for test

sum=sum+s*(float )j/i;

}

cout<<"sum="<<sum;


getch();

return 0;

}


𝒔𝒖𝒎 = 𝟑 +𝟐!

𝟑+

𝟓!

𝟗−

𝟖!

𝟐𝟕


#include <conio.h>

int main()

{

float sum=3.0;

long int f;

clrscr();

for (int n=2,j=3;n<=8;n+=3,j*=3)

{

f=1;

cout <<"n="<<n<<" j="<<j<<"\n";

for (int i=1;i<=n;++i)

f=f*i; //f*=i;

cout<<"Number="<<n<<" Factorial number="<<f<<"\n\n"; // for test

sum=sum+(float )f/j;

}

cout<<"sum="<<sum;


getch();

return 0;

}

58

Q) Write a program to find even numbers among group of numbers


#include <conio.h>

int main()

{

int n,n1;

clrscr();

cout << "Number of numbers:=";

cin >> n;

for (int j=1;j<=n;++j)

{

cout << "Number:=";

cin >> n1;

if (!(n1%2))

cout <<" --- Even number --- \n\n";

}


getch();

return 0;

}

Q) Write a program to find the number and summation of even numbers which accept

division by 4 without remainder among group of numbers


#include <conio.h>

int main()

{

int n,n1;

clrscr();

cout << "Number of numbers:=";

cin >> n;

for (int j=1,n2=0,sum=0;j<=n;++j)

{

cout << "Number:=";

cin >> n1;

if ((!(n1%2)) && (!(n1%4)))

{

sum+=n1;

n2++;

}

}

cout <<"\nSum. of even numbers which accept division by

4:="<<sum<<"\n";

cout<<"No. of even numbers which accept division by 4:="<<n2<<"\n";


getch();

return 0;

}

59

Q) Write a program to find largest number between 5 different numbers


#include <conio.h>

int main()

{

int n,large;

clrscr();

cout << "Number1:=";

cin >> n;

large=n;


{

cout << "Number"<<i<<":=";

cin >> n;

if (n>large)

large=n;

}

cout <<"\nLargest No.:="<<large;


getch();

return 0;

}

Q) Write a program to find smallest number between 5 different numbers


#include <conio.h>

int main()

{

int n,small;

clrscr();

cout << "Number1:=";

cin >> n;

small =n;


{

cout << "Number"<<i<<":=";

cin >> n;

if (n < small)

small =n;

}

cout <<"\n smallest No.:="<< small;


getch();

return 0;

}

60

While (keyword) 12th

week

Repeats execution

Syntax: while ( <expression> ) <statement>

<statement> is executed repeatedly as long as the value of <expression> remains non-zero.

The test takes place before each execution of the <statement>.

You'll find that while statements are just as easy to use as if statements. For example:

while (a < b)

{

printf("%d\n", a);

a = a + 1;

}

This causes the two lines within the braces to be executed repeatedly until a is greater than or

equal to b. The while statement in general works as illustrated to the right.

The for loop in C++ is simply a shorthand way of expressing a while statement. For example,

suppose you have the following code in C++:

x=1;

while (x<10)

{

x++; /* x++ is the same as saying x=x+1 */

}

You can convert this into a for loop as follows:

for(x=1; x<10; x++)

{

}

Note that the while loop contains an initialization step (x=1), a test step (x<10), and an

increment step (x++). The for loop lets you put all three parts onto one line, but you can put

anything into those three parts. For example, suppose you have the following loop:

a=1;

b=6;

while (a < b)

{

a++;

printf("%d\n",a);

}

You can place this into a for statement as well:

for (a=1,b=6; a < b; a++,printf("%d\n",a));

61

It is slightly confusing, but it is possible. The comma operator lets you separate several

different statements in the initialization and increment sections of the for loop (but not in the

test section). Many C++ programmers like to pack a lot of information into a single line of

C++ code; but a lot of people think it makes the code harder to understand, so they break it

up.

Looping: A Real Example

Try This!

Try changing the Fahrenheit-to-Celsius program so that it uses scanf to accept the

starting, ending and increment value for the table from the user.

Add a heading line to the table that is produced.

Create a table that converts pounds to kilograms or miles to kilometers.

Let's say that you would like to create a program that prints a Fahrenheit-to-Celsius

conversion table. This is easily accomplished with a for loop or a while loop:

#include <stdio.h>

int main()

{

int a;

a = 0;

while (a <= 100)

{

printf("%4d degrees F = %4d degrees C\n",a, (a - 32) * 5 / 9);

a = a + 10;

}

return 0;

}

If you run this program, it will produce a table of values starting at 0 degrees F and ending at

100 degrees F. The output will look like this:

0 degrees F = -17 degrees C




40 degrees F = 4 degrees C







The table's values are in increments of 10 degrees. You can see that you can easily change the

starting, ending or increment values of the table that the program produces.

C ++ Errors to Avoid

Putting = when you mean == in an if or while statement

62

Forgetting to increment the counter inside the while loop - If you forget to increment

the counter, you get an infinite loop (the loop never ends).

Accidentally putting a ; at the end of a for loop or if statement so that the statement

has no effect - For example:

for (x=1; x<10; x++);

printf("%d\n",x);

only prints out one value because the semicolon after the for statement acts as the one line the

for loop executes.

If you wanted your values to be more accurate, you could use floating point values instead:

#include <stdio.h>

int main()

{

float a;

a = 0;

while (a <= 100)

{

printf("%6.2f degrees F = %6.2f degrees C\n",

a, (a - 32.0) * 5.0 / 9.0);

a = a + 10;

}

return 0;

}

You can see that the declaration for a has been changed to a float, and the %f symbol

replaces the %d symbol in the printf statement. In addition, the %f symbol has some

formatting applied to it: The value will be printed with six digits preceding the decimal point

and two digits following the decimal point.

Now let's say that we wanted to modify the program so that the temperature 98.6 is inserted

in the table at the proper position. That is, we want the table to increment every 10 degrees,

but we also want the table to include an extra line for 98.6 degrees F because that is the

normal body temperature for a human being. The following program accomplishes the goal:

#include <stdio.h> int main() { float a; a = 0; while (a <= 100) { if (a > 98.6) { printf("%6.2f degrees F = %6.2f degrees C\n", 98.6, (98.6 - 32.0) * 5.0 / 9.0); } printf("%6.2f degrees F = %6.2f degrees C\n", a, (a - 32.0) * 5.0 / 9.0); a = a + 10; } return 0; }

63

This program works if the ending value is 100, but if you change the ending value to 200 you

will find that the program has a bug. It prints the line for 98.6 degrees too many times. We

can fix that problem in several different ways. Here is one way:

#include <stdio.h> int main() { float a, b; a = 0; b = -1; while (a <= 100) { if ((a > 98.6) && (b < 98.6)) { printf("%6.2f degrees F = %6.2f degrees C\n", 98.6, (98.6 - 32.0) * 5.0 / 9.0); } printf("%6.2f degrees F = %6.2f degrees C\n", a, (a - 32.0) * 5.0 / 9.0); b = a; a = a + 10; } return 0; }


#include <iostream.h> #include <conio.h> int main() { int i; clrscr(); i=1; while (i<=5) { cout <<i<<" "; i++; } cout << "\n\nHit any key to continue"; getch(); return 0; }


#include <iostream.h> #include <conio.h> int main() { int i; clrscr(); i=5; while (i>=1) { cout <<i<<" "; i--; } cout << "\n\nHit any key to continue"; getch(); return 0; }

64

Q) Write a program to search for first number 6 between 5 different numbers


#include <conio.h>

int main()

{

int n,i;

clrscr();

cout <<"Number:=";

cin>> n;

i=1;

while ((n!=6) && (i<=4))

{

i++;

cout <<"Number:=";

cin>> n;

}

if (n==6)

cout <<" --- Number 6 is found ---";


getch();

return 0;

}

Q) Write a program to find the summation of numbers of group of numbers and stop

when the result exceed 50 :


#include <conio.h>

int main()

{

int sum=0,n;

clrscr();

while (sum<=50)

{

cout <<"Number:=";

cin>> n;

sum+=n;

}

cout <<"Sum.:="<<sum;


getch();

return 0;

}

65

Q) Write a program to find the summation of the following series and stop when the result

exceed 7 : 𝒔𝒖𝒎 = 𝟒 + 𝟏

𝟐+ 𝟑

𝟑+ 𝟓

𝟒 ….

#include <iostream.h> #include <conio.h> int main() { float sum=4; int i=1,j=2; clrscr(); while (sum<=7) { sum=sum+(float )i/j; cout <<"j:="<<j<<" i="<<i<<"\n"; // for test i+=2; j++; } cout <<"Sum.:="<<sum; cout << "\n\nHit any key to continue"; getch(); return 0; }

Notes:

While (condition)

{

While (condition)

{

}

}

// or

While (condition)

{

for ( expression_1; expression_2; expression_3 )

{

}

}

// or

for ( expression_1; expression_2; expression_3 )

{

While (condition)

{

}

}

66

Do…while loop 13th

week

Syntax: do <statement> while ( <expression> );

<statement> is executed repeatedly as long as the value of <expression> remains non-zero.

The test takes place AFTER each execution of the <statement>.

Example1:

i = 1; n = 1;

do {

n *= i;

i++;

} while (i <= factorial);

Example2:

do

{

printf("%d\n", a);

a = a + 1;

}

while (a < b);



#include <conio.h>

int main()

{

int i;

clrscr();

i=1;

do

{

cout <<i<<" ";

i++;

} while (i<=5);


getch();

return 0;

}

67



#include <conio.h>

int main()

{

int i;

clrscr();

i=5;

do

{

cout <<i<<" ";

i--;

} while (i>=1);


getch();

return 0;

}

Q) Write a program to calculate the area or circumference of rectangle using menu, add

choice 3 for exit #include <iostream.h> #include <conio.h> int main() { int a; int l,w,r; clrscr(); cout << "Length:="; cin >> l; cout << "Width:="; cin >> w; do { clrscr(); cout << "*********************************\n"; cout << "* 1: Area of rectangle *\n"; cout << "* 2: Circumference of rectangle *\n"; cout << "* 3: Exit *\n"; cout << "*********************************\n\n"; cout << "\nChoice:="; cin >> a; switch (a) { case 1: r=l*w; cout << "\n Area of rectangle:="<<r; break; case 2: r=(l+w)*2; cout << "\n Circumference of rectangle:="<<r; break; case 3: cout << "\n\nGood bye at exit"; break; } cout << "\n\nHit any key to continue"; getch(); } while (a!=3); return 0; }

68

Exit

exit terminates the program

Remarks:

exit terminates the calling process. Before termination, exit does the following:

- closes all files

- writes buffered output (waiting to be output)

- calls any registered "exit functions" (posted with at exit)

Q) Write a program to calculate the area or circumference of rectangle using menu, add

choice 3 for exit #include <iostream.h> #include <conio.h> #include <stdlib.h> int main() { int a; int l,w,r; clrscr(); cout << "Length:="; cin >> l; cout << "Width:="; cin >> w; for (;;) { clrscr(); cout << "*********************************\n"; cout << "* 1: Area of rectangle *\n"; cout << "* 2: Circumference of rectangle *\n"; cout << "* 3: Exit *\n"; cout << "*********************************\n\n"; cout << "\nChoice:="; cin >> a; switch (a) { case 1: r=l*w; cout << "\n Area of rectangle:="<<r; break; case 2: r=(l+w)*2; cout << "\n Circumference of rectangle:="<<r; break; case 3: cout << "\n\nGood bye at exit, hit any key to continue"; getch(); exit (0); return 0; break; } cout << "\n\nHit any key to continue"; getch(); } }

69

Break (keyword) 14th

week

Passes control

Syntax: break ;

The break statement causes control to pass to the statement following the innermost enclosing

while, do, for, or switch statement. It causes a loop to terminate early. When it is

encountered, the loop stops and the program jump to the statement immediately following the

loop.

Q) Write a program to search for first number 6 between 5 different numbers

#include <iostream.h> #include <conio.h> int main() { int n; clrscr(); for (int i=1;i<=5;++i) { cout <<"Number:="; cin>> n; if (n==6) { cout <<" --- Number 6 is found ---"; break; } } cout << "\n\nHit any key to continue"; getch(); return 0; }

Continue (keyword)

Syntax: continue ;

Causes control to pass to the end of the innermost enclosing while, do, or for statement, at

which point the loop continuation condition is re-evaluated. It causes a loop to stops its

current iteration and begin the next one. When continue is encountered, all the statements in

the body of the loop that appear after it are ignored, and the loop prepares for the next

iteration.

Q) Write a program to find the summation of 4 different numbers except number 3 or 5

#include <iostream.h> #include <conio.h> int main() { int n; clrscr(); for (int i=1,sum=0;i<=4;++i) { cout <<"Number:="; cin>> n; if ((n==3) || (n==5)) continue; sum+=n; } cout<<"\n\nSum.:="<<sum; cout << "\n\nHit any key to continue"; getch(); return 0; }

70

Math. Functions

pow (real) <MATH.H>

Power function, x to the y

Declaration:

Real: double pow(double x, double y);

long double pow(long double (x), long double (y));

Remarks:

pow calculate x**y.

The complex pow is defined by

pow(base, expon) = exp(expon log(base))

Return Value:

On success, pow return the value calculated, x**y.

If x and y are both 0, they return 1.

If x is real and < 0, and y is not a whole number, these functions set errno to EDOM

(domain error).

Q) Write a program to calculate the cubic number for 4 different numbers


#include <conio.h>

#include <math.h>

int main()

{

double n,c;

clrscr();


{

cout <<"Number:=";

cin>> n;

c=pow(n,3);

cout <<"Cubic Number:="<<c<<"\n\n";

}


getch();

return 0;

}

71

cos, sin, tan (real) <MATH.H>

Cosine, sine, and tangent functions

Declaration:

Real: double cos(double x);

double sin(double x);

double tan(double x);

Remarks:

Real versions

cos compute the cosine of the input value

sin compute the sine of the input value

tan calculate the tangent of the input value

Angles are specified in radians.

Return Value:

On success,

cos return the cosine of the input value (in the range -1 to 1)

sin return the sine of the input value (in the range -1 to 1)

tan returns the tangent of x, sin(x)/cos(x).

#include <stdio.h>

#include <math.h>

int main(void)

{

double result, x;

x = 90;

result = sin(x*3.14/180);

printf("The sin of %.2lf is %.2lf\n", x, result);

//the oputput is: The sin of 90.00 is 1.00

return 0;

}

acos, asin, atan, atan2 (real) <MATH.H>

Arc cosine, arc sine, and arc tangent functions

Declaration:

Real: double acos(double x);

double asin(double x);

double atan(double x);

double atan2(double y, double x);

Remarks:

Real versions

acos of a real value compute the arc cosine of that value

asin of a real value compute the arc sine of that value

atan calculate the arc tangent of the input value

atan2 also calculate the arc tangent of the input value

Real arguments to acos, and asin must be in the range -1 to 1.

72

Return Value:

On success,

acos return the arc cosine of the input value (in the range 0 to pi)

asin return the arc sine of the input value (in the range -pi/2 to pi/2)

atan return the arc tangent of the input value (in the range -pi/2 to pi/2)

atan2 return the arc tangent of y/x (in the range -pi to pi).

atan2 produce correct results even when the resulting angle is near pi/2 or -pi/2 (x near

0).

On error (if the arguments are not in the range -1 to 1), the acos, asin functions return

NAN and set errno to EDOM (domain error).

If both x and y are set to 0, atan2 sets errno to EDOM.

#include <stdio.h>

#include <math.h>

int main(void)

{

double result;

double x = 1.00;

result = asin(x)/(3.14/180);

printf("The arc sin of %.2lf is %.2lf\n", x, result);

//the oputput is: The arc sin of 1.00 is 90.00

return(0);

}

exp (real) <MATH.H>

Real exp calculates e to the xth power

Declaration:

Real: double exp(double x);

long double exp(long double (x));

Remarks:

exp calculates the exponential function e**x.

Return Value:

On success, exp returns e**x

Sometimes the arguments passed to exp produce results that overflow or are incalculable.

On overflow,

exp returns HUGE_VAL

Results of excessively large magnitude cause errno to be set to ERANGE (Result out of

range).

On underflow, exp return 0.0, and errno is not changed.

73

#include <stdio.h>

#include <math.h>

int main(void)

{

double result;

double x = 4.0;

result = exp(x);

printf("'e' raised to the power \

of %lf (e ^ %lf) = %lf\n",x, x, result);

return 0;

}

The output is: 'e' raised to the power of 4.000000

(e^4.000000)=54.598150

sqrt (real) <MATH.H>

Calculates square root

Declaration:

Real: double sqrt(double x);

long double sqrtl(long double @E(x));

Remarks:

sqrt calculates the positive square root of the input value.

Return Value:

Real sqrt return the square root of x.

If x is real and positive, the result is positive.

If x is real and negative, sqrt sets errno to EDOM (domain error).

#include <math.h>

#include <stdio.h>

int main(void)

{

double x = 4.0, result;

result = sqrt(x);

printf("The square root of %lf is %lf\n", x, result);

//the oputput is: The square root of 4.000000 is 2.000000

return 0;

}

74

abs <MATH.H, STDLIB.H, COMPLEX.H>

fabs <MATH.H>

labs <MATH.H, STDLIB.H>

abs (a macro) gets the absolute value of an integer

fabs calculate the absolute value of a floating-point number

labs calculates the absolute value of a long number

Declaration:

abs

real: int abs(int x);

double fabs(double x);

long int labs(long int x);

Remarks:

All of these routines return the absolute value of their argument. Abs is macro; fabs and labs

are functions.

Return Value:

abs:

An integer in the range 0 to 32,767;

fabs: A double

labs: A long

#include <stdio.h>

#include <math.h>

int main(void)

{

int number = -1234;

printf("number: %d absolute value: %d\n", number, abs(number));

//the oputput is: number: -1234 absolute value: 1234

return 0;

}

randomize <STDLIB.H> Initializes random number generator. time.h must included

random <STDLIB.H> Returns a random number: random(num);

random returns a random number between 0 and (num-1).

#include <stdlib.h>

#include <stdio.h>

#include <time.h>

/* prints a random number in the range 0 to 99 */

int main(void)

{

randomize();

printf("Random number in the 0-99 range: %d\n", random (100));

return 0;

}

75

Q) Write a program to solve the following equations, where Q in degree

𝑦 =

tan𝑄 − 𝑒𝑄 𝑥 < 0

−𝑏 + 𝑏2 − 4𝑎𝑐

2𝑎 𝑥 ≥ 0


#include <conio.h>

#include <math.h>

int main()

{

double y,x,a,b,c,Q;

clrscr();

cout <<"x="; cin >>x;

if (x<0)

{

cout <<"Q="; cin >>Q;

y=fabs(tan(Q*3.14/180)-exp(Q));

}

else

{

cout <<"a="; cin >>a;

cout <<"b="; cin >>b;

cout <<"c="; cin >>c;

double bs=b*b-4*a*c;

if ((a) && (bs>0))

y=(-b+sqrt(bs))/2*a;

else

{

cout <<"Error illegal values";

getch();

return 1;

}

}

cout <<"y="<<y;

getch();

return 0;

}

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