What is a do while

C# - do-while

The do-while loop is the same as a 'while' loop except that the block of code will be executed at least once because it first executes the block of code and then it checks the condition.

Syntax:

1. do
   {
       //execute code block
   
   
   } while(boolean expression);

As per the syntax above, do-while loop starts with the 'do' keyword followed by a code block and boolean expression with 'while'.

Example: do-while loop

1. int i = 0;
   
   do
   {
       Console.WriteLine("Value of i: {0}", i);
       
       i++;
   
   } while (i < 10);

OutPut:-

value of i: 0
value of i: 1
value of i: 2
value of i: 3
value of i: 4
value of i: 5
value of i: 6
value of i: 7
value of i: 8
value of i: 9

Just as in the case of the for and while loops, you can break out of the do-while loop using the break keyword.

Example: break inside do-while

1. int i = 0;
   
   do
   {
       Console.WriteLine("Value of i: {0}", i);
       
       i++;
       
       if (i > 5)
           break;
   
   } while (true);

OutPut:-

value of i: 0
value of i: 1
value of i: 2
value of i: 3
value of i: 4
value of i: 5

Nested do-while

The do-while loop can be used inside another do-while loop.

Example: Nested do-while loop

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

OutPut:-

value of i: 0
value of i: 0
value of i: 1
value of i: 1
value of i: 1