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:


  1. 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");
        }
    }











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