Whait is a if statement

C# provides many decision making statements that help the flow of the C# program based on certain logical conditions. C# includes the following decision making statements.

1. if statement
2. if-else statement
3. switch statement
4. Ternary operator:?

Here, you will learn about the if statements.

Syntex:

if(boolean expression)
{
    // execute this code block if expression evalutes to true
}

The if statement contains boolean expression inside brackets followed by a single or multi-line code block. At runtime, if a boolean expression is evaluates to true then the code block will be executed.

Consider the following example where the if condition contains true as an expression.

Example: if condition

1. if(true)
   {
       Console.WriteLine("This will be displayed.");
   }
   
   if(false)
   {
       Console.WriteLine("This will not be displayed.");
   }

As mentioned above, if statement can contain a boolean expression. An expression which returns either true or false. Following example uses the logical expression as a condition:

Example: if condition

1. int i = 10, j = 20;
   
   if (i > j)
   {
       Console.WriteLine("i is greater than j");
   }
   
   if (i < j)
   {
       Console.WriteLine("i is less than j");
   }        
   
   if (i == j)
   {
       Console.WriteLine("i is equal to j");
   }   

if-else Statement

C# also provides for a second part to the if statement, that is else. The else statement must follow if or else if statement. Also, else statement can appear only one time in a if-else statement chain.

Example: if else

1. int i = 10, j = 20;
   
   if (i > j)
   {
       Console.WriteLine("i is greater than j");
   }
   else
   {
       Console.WriteLine("i is either equal to or less than j");
   }

else if Statement

The 'if' statement can also follow an 'else' statement, if you want to check for another condition in the else part.

Example: else if

1. static void Main(string[] args)
   {
       int i = 10, j = 20;
   
       if (i > j)
       {
           Console.WriteLine("i is greater than j");
       }
       else if (i < j)
       {
           Console.WriteLine("i is less than j");
       }
       else
       {
           Console.WriteLine("i is equal to j");
       }
   }

Nested if Statements

C# alows nested if else statements. The nested 'if' statement makes the code more readable.

1. int i = 10;
   
   if (i > 0)
   {
       if (i <= 100)
       {
           Console.WriteLine("i is positive number less than 100");
       }
       else 
       {
           Console.WriteLine("i is positive number greater than 100");
       }
   }

2.