C#If ... Else

C# Conditions and If Statements

You already know that C# supports familiar comparison conditions from mathematics, such as:

• Less than:a < b
• Less than or equal to:a <= b
• Greater than:a > b
• Greater than or equal to:a >= b
• Equal toa == b
• Not Equal to:a != b

You can use these conditions to perform different actions for different decisions.

C# has the following conditional statements:

• Useif to specify a block of code to be executed, if a specified condition is true
• Useelse to specify a block of code to be executed, if the same condition is false
• Useelse if to specify a new condition to test, if the first condition is false
• Useswitch to specify many alternative blocks of code to be executed

The if Statement

Use theif statement to specify a block of C# code to be executed if a condition isTrue.

if (condition) { // block of code to be executed if the condition is True}

In the example below, we test two values to find out if 20 is greater than 18. If the condition isTrue, print some text:

if (20 > 18) {  Console.WriteLine("20 is greater than 18");}

We can also test variables:

int x = 20;int y = 18;if (x > y) {  Console.WriteLine("x is greater than y");}

Example explained

In the example above we use two variables,x andy, to test whether x is greater than y (using the> operator). As x is 20, and y is 18, and we know that 20 is greater than 18, we print to the screen that "x is greater than y".