Conditions In C# C-Sharp

C#
LECTURE#6
Abid Kohistani.
GC Madyan Swat

Conditions and If Statements
C# supports the usual logical conditions from mathematics:
Less than: a < b
Less than or equal to: a <= b
Greater than: a > b
Greater than or equal to: a >= b
Equal to a == b
Not Equal to: a != b

Conditions and If Statements Cont..
C# has the following conditional statements:
Use if to specify a block of code to be executed, if a specified condition is true
Use else to specify a block of code to be executed, if the same condition is false
Use else if to specify a new condition to test, if the first condition is false
Use switch to specify many alternative blocks of code to be executed

The if Statement
Use the if statement to specify a block of C# code to be executed if a condition is True.
Syntax:
Example:
if (condition)
{
// block of code to be executed if the condition
is True
}
int x = 20;
int y = 18;
if (x > y)
{
Console.WriteLine("x is greater than y");
}

The else Statement
Use the else statement to specify a block of code to be executed if the condition is False.
Syntax:
Example:
if (condition)
{
// block of code to be executed if the condition is True
}
else
{
// block of code to be executed if the condition is False
}
int time = 20;
if (time < 18)
{
Console.WriteLine("Good day.");
}
else
{
Console.WriteLine("Good evening.");
} // Outputs "Good evening."

The else if Statement
Use the else if statement to specify a new condition if the first condition is False.
if (condition1)
{
// block of code to be executed if condition1 is True
}
else if (condition2)
{
// block of code to be executed if the condition1 is false and condition2 is True
}
Else
{
// block of code to be executed if the condition1 is false and condition2 is False
}
int time = 22;
if (time < 10)
{
Console.WriteLine("Good morning.");
}
else if (time < 20)
{
Console.WriteLine("Good day.");
}
else
{
Console.WriteLine("Good evening.");
} // Outputs "Good evening."
Syntax Example

Short Hand If...Else (Ternary Operator)
ternary operator consists of three operands. It can be used to replace multiple lines of code with a single
line. It is often used to replace simple if else statements:
Syntax:
Example:
variable = (condition) ? expressionTrue : expressionFalse;
int time = 20;
string result = (time < 18) ? "Good day." : "Good evening.";
Console.WriteLine(result);

Switch Statements
Use the switch statement to select one of many code blocks to be executed. This is how it works:
The switch expression is evaluated once
The value of the expression is compared with the values of each case
If there is a match, the associated block of code is executed
The break and default keywords will be described later in this chapter
switch(expression)
{
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
break;
}
Syntax:

Switch Example
The example below uses the weekday
number to calculate the weekday name:
int day = 4;
switch (day)
{
case 1:
Console.WriteLine("Monday");
break;
case 2:
Console.WriteLine("Tuesday");
break;
case 3:
Console.WriteLine("Wednesday");
break;
case 4:
Console.WriteLine("Thursday");
break;
case 5:
Console.WriteLine("Friday");
break;
case 6:
Console.WriteLine("Saturday");
break;
case 7:
Console.WriteLine("Sunday");
break;
} // Outputs "Thursday" (day 4)

The break Keyword
When C# reaches a break keyword, it breaks out of the switch block. This will stop the execution of more
code and case testing inside the block. When a match is found, and the job is done, it's time for a break.
There is no need for more testing.
switch(expression)
{
case x:
// code block
break;
case y:
// code block
break;
default:
// code block
break;
}
Syntax:

The default Keyword
The default keyword is optional and specifies some code to run if there is no case match:
int day = 4;
switch (day)
{
case 6:
Console.WriteLine("Today is Saturday.");
break;
case 7:
Console.WriteLine("Today is Sunday.");
break;
default:
Console.WriteLine("Looking forward to the Weekend.");
break;
} // Outputs "Looking forward to the Weekend."
Syntax:

Conditions In C# C-Sharp

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