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A while loop statement in C# repeatedly executes a target statement as long as a given condition is true.

Syntax

The syntax of a while loop in C# is −

while(condition) {
   statement(s);
}

Here, statement(s) may be a single statement or a block of statements. The condition may be any expression, and true is any non-zero value. The loop iterates while the condition is true.

When the condition becomes false, program control passes to the line immediately following the loop.

Flow Diagram

Here, key point of the while loop is that the loop might not ever run. When the condition is tested and the result is false, the loop body is skipped and the first statement after the while loop is executed.

Example

 

 
using System;

namespace Loops {
   class Program {
      static void Main(string[] args) {
         /* local variable definition */
         int a = 10;

         /* while loop execution */
         while (a < 20) {
            Console.WriteLine("value of a: {0}", a);
            a++;
         }
         Console.ReadLine();
      }
   }
} 
 

When the above code is compiled and executed, it produces the following result −

value of a: 10
value of a: 11
value of a: 12
value of a: 13
value of a: 14
value of a: 15
value of a: 16
value of a: 17
value of a: 18
value of a: 19

Nested while loop:

In this section we will discuss aboultNested while. Nested while loop is allowed in C#

Syntax

int i = 0;

while (i < 2)
{
    Console.WriteLine("Value of i: {0}", i);
    int j = 1;

    i++;

    while (j < 2)
    {
        Console.WriteLine("Value of j: {0}", j);
        j++;
    }
}

Output

Value of i: 0 
Value of j: 1 
Value of i: 1 
Value of j: 1 

Please make sure that conditional expression evaluates to false at some point to avoid infinite loop.

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