advanced computer...
TRANSCRIPT
Console Input and Output Functions
• Console Output Functions:
– Console.Write()
– Console.WriteLine()
Advanced Computer Programming
Console.Write()
C# program that uses Console.Write
using System;
class Program
{
static void Main()
{
Console.Write("One "); // <-- This writes the word.
Console.Write("Two "); // <-- This is on the same line.
Console.Write("Three"); // <-- Also on the same line.
Console.WriteLine(); // <-- This writes a newline.
Console.WriteLine("Four"); // <-- This is on the next line.
Console.Readline();
}
}
Advanced Computer Programming
Output
One Two ThreeFour
Console.Write()
•using System;•using System.Collections.Generic;•using System.Linq;•using System.Text;•
•namespace Example1•{• class Program• {•
• static void Main()• {• int num=2;• Console.Write("\nPrevious Value:\t{0}", num);• num++;• Console.Write("\nCurrent Value:\t{0}", num);•
• Console.WriteLine("\n\n\n----------------");• Console.Write("\nPrevious Value:\t{0}", num);• num--;• Console.Write("\nCurrent Value:\t{0}", num);• Console.ReadLine();• }• }•}
Advanced Computer Programming
Console.Writeline
• The Write () method outputs one or more values to the screen without a new line character.
• The WriteLine() always appends a new line character to the end of the string. this means any subsequent output will start on a new line.
Console.WriteLine()
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System;class Program{
static void Main(){
Console.Write("Box");Console.Write("Table");Console.Write("chair");Console.WriteLine();Console.WriteLine("desk");
Console.Readline();}
}
Console.WriteLine()
using System;
class Program
{
static void Main()
{
// Write an int with Console.WriteLine.
int valueInt = 4;
Console.WriteLine(valueInt);
// Write a string with the method.
string valueString = "Your string";
Console.WriteLine(valueString);
// Write a bool with the method.
bool valueBool = false;
Console.WriteLine(valueBool);
}
}
Output 4
Your string
False
Input Functions: Console.ReadLine
using System;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string firstName = "John";
string lastName = "Doe";
Console.WriteLine("Name: " + firstName + " " + lastName);
Console.WriteLine("Please enter a new first name:");
firstName = Console.ReadLine();
Console.WriteLine("New name: " + firstName + " " + lastName);
Console.ReadLine();
}
}
}
Read, ReadLine, ReadKey
Read() Readline() ReadKey()
Accept the string value
and return integer
value.
Accept the string and
return String
Accept the character and
return Character
Console.Read
using System;
class Program
{
static void Main()
{
// This program accepts console input.
// ... When the enter key is pressed, the Read method returns the first time.
// ... Then, each call to Read accesses one further character from the input.
int result;
while ((result = Console.Read()) != 0)
{
Console.WriteLine("{0} = {1}", result, (char)result);
}
}
}
Convert Function for Integer Inputs
using System;
class Program
{
static void Main()
{
Console.WriteLine("How many students would you like to enter?");
int amount = Convert.ToInt32(Console.Read());
Console.WriteLine("{0} {1}", "amount equals", amount);
for (int i=0; i < amount; i++)
{
Console.WriteLine("Input the name of a student");
String StudentName = Console.ReadLine();
Console.WriteLine("the Students name is " + StudentName);
}
}
}
VALUES & VARIABLES
Advanced Computer Programming
Properties of variables:
Should have a type
Stores data
Case sensitive
Their names can not start with a number
Reserved keywords can not be used as variable names
VALUES & VARIABLES
Advanced Computer Programming
How to define a variable:
int x = 3;
Type
Variable
Value
Semicolon: End of
statement
VALUES & VARIABLES
Advanced Computer Programming
How to define a variable:
int nInteger;
string sString;
int nInteger = 42;
string sString = "This is a string!";
int nInteger;
string sString;
...
nInteger = 42;
sString = "This is a string!";
Double quotes
represents a string
VARIABLE TYPES
Advanced Computer Programming
The Boolean Types:
Boolean types are declared using the keyword, bool. They have two values: true or false. In other
languages, such as C and C++, boolean conditions can be satisfied where 0 means false and
anything else means true. However, in C# the only values that satisfy a boolean condition is true
and false, which are official keywords.
using System;
class Booleans{
public static void Main(){
bool content = true;bool noContent = false;
Console.WriteLine("It is {0} that C# Station provides C# programming language content.", content);Console.WriteLine("The statement above is not {0}.", noContent);
}}
VARIABLE TYPES
Advanced Computer Programming
Integral Types:
In C#, an integral is a category of types. For anyone confused because the word Integral sounds like amathematical term, from the perspective of C# programming, these are actually defined as Integral typesin the C# programming language specification. They are whole numbers, either signed or unsigned, and thechar type. The char type is a Unicode character, as defined by the Unicode Standard. For more information,visit The Unicode Home Page.
Type Size (in bits) Rangesbyte 8 -128 to 127byte 8 0 to 255short 16 -32768 to 32767ushort 16 0 to 65535int 32 -2147483648 to 2147483647uint 32 0 to 4294967295long 64 -9223372036854775808 to 922337203685477580ulong 64 0 to 18446744073709551615char 16 0 to 65535
VARIABLE TYPES
Advanced Computer Programming
Integral Types:
In C#, an integral is a category of types. For anyone confused because the word Integral sounds like amathematical term, from the perspective of C# programming, these are actually defined as Integral typesin the C# programming language specification. They are whole numbers, either signed or unsigned, and thechar type. The char type is a Unicode character, as defined by the Unicode Standard. For more information,visit The Unicode Home Page.
short 2 byte
short sval = -12;
ushort 2 bytes
ushort sval= 12;
int 4 bytes
int nval = -12500;
uint 4 bytes
uint nval = 12500;
long 8 bytes
long lVal = -548444101;
ulong 8 bytes
ulong lVal = 548444101;
VARIABLE TYPES
Advanced Computer Programming
Floating Point and Decimal Types:
A C# floating point type is either a float or double. They are used any time you need to represent a realnumber, as defined by IEEE 754. For more information on IEEE 754, visit the IEEE Web Site. Decimal typesshould be used when representing financial or money values.
Type Size (in bits) precision Rangefloat 32 7 digits 1.5 x 10-45 to 3.4 x 1038
double 64 15-16 digits 5.0 x 10-324 to 1.7 x 10308
decimal 128 28-29 decimal places 1.0 x 10-28 to 7.9 x 1028
float 4 bytes
– float fVal = -1,2;
double 8 bytes
– double dVal = -3.565;
decimal 16 bytes
– decimal dVal = -3456.343;
VARIABLE TYPES
Advanced Computer Programming
The String Type:
A string is a sequence of text characters. You typically create a string with a string literal, enclosed inquotes: "This is an example of a string.”
string myString = “Hello!”; Hello!Verbatim strings
string myString = @“2.5”” disk”; 2.5” diskstring e = "Joe said \"Hello\" to me"; Joe said "Hello" to mestring f = @"Joe said ""Hello"" to me"; Joe said "Hello" to mestring g = "\\\\server\\share\\file.txt"; \\server\share\file.txtstring h = @"\\server\share\file.txt"; \\server\share\file.txt
Some characters aren't printable, but you still need to use them in strings. Therefore, C# has a specialsyntax where characters can be escaped to represent non-printable characters. For example, it is commonto use newlines in text, which is represented by the '\n' char. The backslash, '\', represents the escape.When preceded by the escape character, the 'n' is no longer interpreted as an alphabetical character, butnow represents a newline.
You may be now wondering how you could represent a backslash character in your code. We have toescape that too by typing two backslashes, as in '\\'.
VARIABLE TYPES
Advanced Computer Programming
Escape Sequence Meaning\' Single Quote\" Double Quote\\ Backslash\0 Null, not the same as the C# null value\a Bell\b Backspace\f Form Feed\n Newline\r Carriage Return\t Horizontal Tab\v Vertical Tab
VARIABLE TYPES
Advanced Computer Programming
Expressions:
Expressions are used for performing operations over variables.
Return a value of known type. Two types of expressions
Operators Functions
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:
They need more than one variable. Performs mathematical operations
+ (addition operation) - (subtraction operation) * (multiplication operation) / (division operation) % (modulus operation) ….
Category (by precedence) Operator(s) Associativity
Primary x.y f(x) a[x] x++ x-- leftUnary + - ! ~ ++x --x (T)x rightMultiplicative * / % leftAdditive + - leftShift << >> leftRelational < > <= >= leftEquality == != rightLogical AND & leftLogical XOR ^ leftLogical OR | leftConditional AND && leftConditional OR || leftNull Coalescing ?? LeftTernary ?: rightAssignment = *= /= %= += -= <<= >>= &= ^= |= => right
Left associativity means that operations are evaluated from left to right. Right associativity mean all operations occur from right to left, such as assignment operators where everything to the right is evaluated before the result is placed into the variable on the left.
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:Abbreviations
int m = 5;int n = 4;
m = m + n; equals m += n; In other words in the end of both expressions m will have value of 9 and the value of n will not be changed.
They operate on one variable
++ is increment operator
i++; i = i + 1;
-- is decrement operator
i --; i = i – 1;
Prefix and postfix operators will yield to different results. i.e. “i++” and “++i” are not
same.
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:Abbreviations
++k The result of the operation is the value of the operand after it has been incremented.
k++ The result of the operation is the value of the operand before it has been incremented.
--k The result of the operation is the value of the operand after it has been decremented.
k-- The result of the operation is the value of the operand before it has been decremented.
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:Abbreviations
int k=0, m;
m = ++k;
Values of m and k will be 1
int k=0, m;
m = k++;
m will be 0 and
k will be 1
int k=5, m, n=2;
m = --k + n;
m will be 6 and
k will be 4
int k=0, m, n=7;
m = k++ + --n;
m will be 6 and
k will be 1 and
n will be 6
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:Exercise
What will be the values of the variables after code piece below is executed?
int i, j, k;
i = 2;
j = 3 + i++;
k = 3 + ++i;
i *= ++k + j--;
i /= k-- + ++j;
VARIABLE TYPES
Advanced Computer Programming
Arithmetic operations:Exercise
Assuming that line of codes are independent, what will be the value of variable m after each line is executed?
int i = 0, j = 6, k = 4 , m = 5;
•m = k-- + ++i;
•m *= j % 4;
•m += k++ + (j-- * ++i);
http://msdn.microsoft.com/en-us/library/6a71f45d.aspx
VARIABLE TYPES
Advanced Computer Programming
Order of Operations: Rules that defines which procedures should be performed first.
In C# language some operators have execution privilege over others.
To predict the result of an expression first we should know the order of operations.
PEMDAS phrase may help to remember the order. P Parenthesis
E Exponent
M Multiplication
D Division
A Addition
S Subtraction
1 + 2 * 3 - 4 / 5 = ?
1 + (2 * 3) – (4 / 5)
6.2
VARIABLE TYPES
Advanced Computer Programming
Order of Operations:If we use all numbers in integer type then the result will be integer (In other words fraction
will be removed)
4/5 = 0
(integer division)
1 + (2 * 3) – (4 / 5)
7
VARIABLE TYPES
Advanced Computer Programming
Order of Operations:If we use all numbers in integer type then the result will be integer (In other words fraction
will be removed)
Different data types may yield different results in same operations.
Write and execute the codes in the next slides.
Explain the difference between results.
VARIABLE TYPES
Advanced Computer Programming
Characters:char 1 byte 0-256
'a' 'z' 'A' 'Z' '?' '@' '0' '9'
Special characters are represented by using “\” prefix.
'\n' : new line'\t' : tab'\'' : single quote'\\' : backslash
VARIABLE TYPES
Advanced Computer Programming
String:Sequence of characters.
Example: “Hello!”“first line\n second line \n third line”“” Empty string
“string” ClassUnicode – 16 bitExample:
string myString = “Hello!”;
Verbatim stringsstring myString = @“2.5”” disk”;
Result: “Hello world!”
VARIABLE TYPES
Retrieve a substring from a string
string Substring()
Advanced Computer Programming
String:
Result : “llo”
EXERCISE
Put your name and surname into two string variables.
Concatenate two strings.
Write the result to the console.
VARIABLE TYPES
C# language has built-in “DateTime” structure to represent date and time values.
We can store “year, month, day, hour, minute, second” values in a DateTime structure.
Advanced Computer Programming
Date Time:
DateTime dt = new DateTime(year, month, day);
Type
Variable name
Creating a new object
Initial values
VARIABLE TYPES
C# language has built-in “DateTime” structure to represent date and time values.
We can store “year, month, day, hour, minute, second” values in a DateTime structure.
Advanced Computer Programming
Date Time:
Type
A new DateTimeobject is created