chap 2 input output dti2143

Chapter 2 :INPUT AND OUTPUT

PROCESSDTI 2143: Computer Programming

OBJECTIVES-PART 1

To understand input and output streams. To be able to use all print formatting capabilities. To be able to use all input formatting capabilities. To be able to print with field widths and precisions. To be able to use formatting flags in the printf format

control string. To be able to output literals and escape sequences.

PRINTF() FUNCTION

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printf()

To display output/data

To send data to output device

printf(“output_format”,print_list) ;

printf(“First example“) ;

printf(“The bread price is RM %lf“,price) ;

function

format

example

PRINTF() FUNCTION (CONTINUED..)

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Output_format

mayconsists

text

placeholder

combination

Inside“ ”

Print_list

variable

constant

expression

function_name

mayconsist

printf(“output_format”,print_list) ;format

PRINTF() FUNCTION (CONT..)

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Example 1:

printf(“Universiti Tun Hussein Onn Malaysia”);

Output format -Text

Output:

Universiti Tun Hussein Onn Malaysia

PRINTF() FUNCTION (CONT..)

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Example 2:

printf(“%lf”, salary);

Format output-placeholdervariable

Output:

PRINTF() FUNCTION (CONTINUED..)

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Example 3:

printf(“Monthly salary is RM %lf”, salary);

Output format -Text

placeholder

variable

Output:

Monthly salary is RM

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PRINTF() (FUNCTION CONTINUED..)

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Example 4:

const float porosity = 16.78;printf(“The porosity of sand = %lf ”, porosity);

Output format -Text

The porosity of sand = 16.780001

Output:

constant

placeholder

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PRINTF() FUNCTION (CONT..)

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escape Character

function Additional formatting to be performed with the printf() function

Character Explanation\n New line

\t Tab

\a Beep sound

PRINTF() FUNCTION (CONT..)

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Placeholder

function

A symbol beginning with % in a format string that indicates where to display the output value

format

Using percent symbol (%) followed by characterwhich represent particular data type

Data type

Placeholder Output to be print

int %d Integer number

double %lf Floating number

float %f Floating number

char %c Character

char %s String

PRINTF() FUNCTION (CONT..)

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char huruf1, huruf2;huruf1 = ‘B’;huruf2 = ‘P’;

printf(“%c%c%c”, ‘A’, ‘L’, ‘I’);printf(“\nI live in %c%c”,huruf1,huruf2);

Example 5 (Printing character value ) :

Output:

ALII live in BP

PRINTF() FUNCTION (CONT..)

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int number1, number2;

printf(“My house number is %d”, 26);number2=10;printf(“\n\tNumber %d and %d”,number1,number2);number2=2;number1= 15;printf(“\nNumber %d and %d”,number2,number1);

Example 6 (Printing integer value) :

Output:My house number is 26

Number 906 and 10Number 2 and 15

PRINTF() FUNCTION (CONTINUED..)

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double sahih1, sahih2;

printf(“The value of pi is %lf”, 3.142);sahih1= 23.46;printf(“\nThe value of sahih1 is %lf”,sahih1);sahih2= 15.78;printf(“\tThe value of sahih2 is %lf’,sahih2);

Example 6 (Printing floating point number) :

Output:

The value of pi ialah 3.142The value of sahih1 is 23.46 The value of sahih2 is 15.78

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PRINTF() FUNCTION (CONT..)

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1. Given a = 2, b = 4. What are the output produced by the following statements?

a) printf(“The additionresult of two number >> %d”,a + b);

b) printf(“\nThe addition of %d and %d “, a,b);

2. Write a valid C programming statement to display the following output (use variables):

(Notes: Given the value of variable x = 2.5 and y = 3.1

The value of x is 2.5cm and y is 3.1cm

The multiplication result of x and y is 7.75cm

SCANF() FUNCTION

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scanf() To accept input

To read input from keyboard

scanf(“input_format”,&variable_list) ;

scanf(“%d”,&nom) ;

scanf(“%s %d %lf”,&name,&age,&weight) ;

function

format

example

SCANF() FUNCTION (CONT..)

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placeholder

output_list variableconsist

input_formatconsists example

%d @ %c @%lf

constantexpression function

Not allowed!!!

‘&’ symbolKnown as ampersand

Variable address/location reference

SCANF() FUNCTION (CONT..)

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Example1:

scanf(“%lf %d %c”,&float_num, &num,&letter);

Placeholder

Every variables to be used in the program MUST be declared!!!

Variable

The above statement is valid!

Warning!!!!!

SCANF() FUNCTION (CONT..)

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Example 2:

scanf(“ %d ”, 15);

Placeholder

Constant value

The above statement is INVALID!

scanf(“ %lf ”, &price + 0.05);

Conversion character

Expression

The above statement is INVALID!

SCANF() FUNCTION (CONT..)

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Example 3(program code):

#include <stdio.h>void main(){ int semester; float CPA;

printf(“Enter the semester : “); scanf(“%d”, &semester); printf(“\nEnter your CPA : “); scanf(“%lf”,&CPA); printf(“\nYour CPA for semester %d is %f”,semester,CPA);}

?

?

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SCANF() FUNCTION (CONT..)

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Output:

Enter the semester : 3Enter your CPA : 3.45Your CPA for semester 3 is 3.45

SCANF() FUNCTION (CONTINUE..)

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1).Write the scanf() statement to accept the following type of variables:

a. char jantina;

b. float berat;

c. int tempoh;

2).State whether the following scanf() statements is VALID or INVALID.

Given the following declaration:

int a, b;

char c;

a) scanf(“%d”, &a + b);

b) scanf(“%c”, &c);

c) scanf(“%d”,&a,&b);

OTHER I/O FUNCTIONS

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Similar functions used in the input and output operations in C programming such as:

getchar() and putchar() functiongetch() dan putch() functiongets() dan puts() function

OTHER I/O FUNCTIONS

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getchar()

To read any input from input device as character data type

variable= getchar();

char letter;printf(“Enter one letter>>”);letter= getchar();

function

format

example usage

OTHER I/O FUNCTIONS

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putchar()To display output in a single

character value

putchar(variable);

printf(“The input letter is ”);putchar(letter);

function

format

example usage

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OTHER I/O FUNCTIONS

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#include <stdio.h>void main(){ char letter;

printf(“Enter one letter : “); letter = getchar(); printf(“The input letter is\t“); putchar(letter);}

Example 1: getchar() and putchar()

Enter one letter : eThe input letter is e

OTHER I/O FUNCTIONS

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#include <stdio.h>void main(){ int number;

printf(“Enter one number : “); number = getchar(); printf(“The input number is %d\n“,number); putchar(number);}

Example 2: getchar() and putchar()

Enter one number : 123The input number is 491

However, it can also be program like this :

OTHER I/O FUNCTIONS

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getch()

To read an input and terminate the program automatically

variable= getch();

char letter;printf(“Enter one letter >>”);letter= getch();

function

format

example

getch() have same function like getchar(), but different action

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OTHER I/O FUNCTIONS

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#include <stdio.h>void main(){ int number;

printf(“Enter one number : “); number = getchar(); printf(“The input number is %d\n“,number); getch();}

Example 3: getch()

We can use getch() to hold user screen, and terminate onceany input is read

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OTHER I/O FUNCTIONS

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putch()

To display output , have similar function like

putchar

putch (variable);

printf(“The input letter is ”);putch(letter);

function

format

example

OTHER I/O FUNCTIONS

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gets()To read string input from input device

gets(variable);

char name[20];printf(“Enter your name >>”);gets(name);

function

format

example

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OTHER I/O FUNCTIONS

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#include <stdio.h>void main(){ char name[20];

printf(“Enter your name : “); scanf(“%s”,&name); printf(“Your name is %s “,name); getch();}

Example 4: gets()

If we use scanf() function to read string input, it will only takes the first data between two words (if any)

Enter your name: Siti AminahYour name is Siti

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OTHER I/O FUNCTIONS

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#include <stdio.h>void main(){ char name[20];

printf(“Enter your name : “); gets(name); printf(“Your name is %s\n“,name); getch();}

Example 5: gets()

If we use gets() function to read string input, it will takes all thedata including space between two words (if any)

Enter your name: Siti AminahYour name is Siti Aminah

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OTHER I/O FUNCTIONS

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puts() To display string output to output device

puts (variable);

printf(“Your name is ”);puts(name);

functions

format

example

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OUTPUT FORMATTING

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Integer formatting

To format the display of an integervalue

%spaced

Use the integer formatting in theoutput statement

functions

format

Where to use?

How it works?• Provide spaces according to formatting• Put the value to display starting from right to left side• If there is – sign in the formatting, values will be printed starting from left to right side

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Output Formatting

Integer formatting

exampleprintf(“%3d”,123);

output 123

printf(“%5d”,123);output _ _123

printf(“%10d”,123);output _ _ _ _ _ _ _123

printf(“%-6d”,123);output 123_ _ _

printf(“%-4d%4d”,123,456);output 123_ _456

Assume _ isan empty

space

example

example

example

example

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OUTPUT FORMATTING

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#include <stdio.h>

void main(){ printf(“%d “,123); printf(“\n%3d “,123); printf(“\n%5d “,123); print(“\n%10d”,123); print(“\n%-6d”,123); print(“\n%-4d%d4d”,123,456);}

Example 1: Integer formatting

Output?

OUTPUT FORMATTING

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Floatingnumber

formatting

To format the display of the floatingnumber value

%spacef

Use in the output statement

functions

format

Where to use?

• Provide spaces according to formatting• Put the value to display starting from right to left side• If there is – sign in the formatting, values will be printed starting from left to right side

How it works?

OUTPUT FORMATTING

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Floating number formattingformat %spacef

example printf(“%10f”,57.78);

output _57.780000

example printf(“%15f”,57.78);

output _ _ _ _ _ _57.780000

exampleprintf(“%-10f”,57.78);

output 57.780000_

example printf(“%15f”,57.78);

output 57.780000_ _ _ _ _ _

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Output formatting

Floating point exampleformat %f

example printf(“%.3f”,57.78);

output 57.780

printf(“%.2f”,57.78);output 57.78

printf(“%.1f”,57.78);output 57.8

printf(“%6.2f”,57.78);output 57.78_

printf(“%-6.2f”,57.78); _57.78output

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example

example

example

example

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Output formatting

String formatformat %<space>c

char huruf = ‘A’;printf(“%c”,huruf);printf(“%2c”,huruf);printf(“%-5c”,huruf);

A_AA_ _ _ _

output

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example

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Format Output (cont..)

String formattingformat %<spaces> s

char ayat[] =“KUITTHO PARIT RAJA”printf(“%s”,ayat);printf(“%4s”,ayat);printf(“%22s”,ayat);printf(“%.7s”,ayat);printf(“%-20.13s”,ayat);

KUITTHO PARIT RAJAKUITTHO PARIT RAJA_ _ _ _KUITTHO PARIT RAJAKUITTHOKUITTHO PARIT_ _ _ _ _ _ _

output

QUICK RECAPConversion specifier Description

%d Read an optionally signed decimal integer

%i Read an optionally signed decimal

%o Read an octal integer

%u Read an unsigned decimal integer

%x Read a hexadecimal integer

%e,%f,%g Read a floating-point value

%l Place before any floating-point specifiers to indicate that a double or long double value is to be input

%c Read a character

%s Read a string

Table 1- Conversion specifiers for scanf

PRINTING INTEGERS

An integer is a whole number, such as 776, 0, or -52 that contains no decimal point

Table 1- Integer conversion specifiers

Conversion specifier

Description

%d Display as a signed decimal integer

%o Display as an unsigned octal integer

%u Display as an unsigned decimal integer

%x Display as an unsigned hexadecimal integer

PRINTING FLOATING-POINT NUMBERS

Floating-point value contains a decimal point as in 33.5, 0.0 or -657.983

Conversion specifier

Description

%e Display a floating-point value in exponential notation

%f Display floating-point values in fixed-point notation

%g Display a floating-point value in either the floating-point form f or the exponential form e

%l Place before any floating-point conversion specifier to indicate that a long double floating-point value is displayed

Table 3- floating-point conversion specifies

symbolic ASCII symbolic ASCII

\0 null \a alert (bell)

\b backspace \v Vertical tab

\n New line \t Horizontal tab

\r Carriage return \\ or \* *\ comment

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CHARACTER CONSTANTS