C# if-else

In C# programming, the if statement is used to test the condition. There are various types of if statements in C#.

if statement
if-else statement
nested if statement
if-else-if ladder

if Statement

The C# if statement tests the condition. It is executed if condition is true.

Syntax

if(condition){
//code to be executed
}

Example

snippet

using System;    
public class IfExample
    {
       public static void Main(string[] args)
        {
            int num = 10;
            if (num % 2 == 0)
            {
                Console.WriteLine("It is even number");
            }
            
        }
    }

Output

It is even number

if-else Statement

The C# if-else statement also tests the condition. It executes the if block if condition is true otherwise else block is executed.

Syntax

if(condition){
//code if condition is true
}else{
//code if condition is false
}

Example #1

snippet

using System;    
public class IfExample
    {
        public static void Main(string[] args)
        {
            int num = 11;
            if (num % 2 == 0)
            {
                Console.WriteLine("It is even number");
            }
            else
            {
                Console.WriteLine("It is odd number");
            }
            
        }
    }

Output

It is odd number

Example #2

C# If-else Example: with input from user

In this example, we are getting input from the user using Console.ReadLine() method. It returns string. For numeric value, you need to convert it into int using Convert.ToInt32() method.

snippet

using System;    
public class IfExample
    {
       public static void Main(string[] args)
        {
            Console.WriteLine("Enter a number:");
            int num = Convert.ToInt32(Console.ReadLine());

            if (num % 2 == 0)
            {
                Console.WriteLine("It is even number");
            }
            else
            {
                Console.WriteLine("It is odd number");
            }
            
        }
    }

Output

Enter a number:11 It is odd number

Output

Enter a number:12 It is even number

if-else-if ladder Statement

The C# if-else-if ladder statement executes one condition from multiple statements.

Syntax

if(condition1){
//code to be executed if condition1 is true
}else if(condition2){
//code to be executed if condition2 is true
}
else if(condition3){
//code to be executed if condition3 is true
}
...
else{
//code to be executed if all the conditions are false
}

Example

C# If else-if Example

snippet

using System;    
public class IfExample
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Enter a number to check grade:");
            int num = Convert.ToInt32(Console.ReadLine());

            if (num <0 || num >100)
            {
                Console.WriteLine("wrong number");
            }
            else if(num >= 0 && num < 50){
                Console.WriteLine("Fail");
            }
            else if (num >= 50 && num < 60)
            {
                Console.WriteLine("D Grade");
            }
            else if (num >= 60 && num < 70)
            {
                Console.WriteLine("C Grade");
            }
            else if (num >= 70 && num < 80)
            {
                Console.WriteLine("B Grade");
            }
            else if (num >= 80 && num < 90)
            {
                Console.WriteLine("A Grade");
            }
            else if (num >= 90 && num <= 100)
            {
                Console.WriteLine("A+ Grade");
            }
        }
    }

Output

Enter a number to check grade:66 C Grade

Output

Enter a number to check grade:-2 wrong number