C# - While Loop

A loop statement allows a program to execute a given block of codes repeatedly under a given condition. This enables a programmer to write programs in fewer lines of code and enhance the code readability. C# has following types of loop to handle the looping requirements:

while loop
do-while loop
for loop

The While Loop

While loop allows a set of statements to be executed repeatedly until a given condition is true. The While loop can be viewed as a repeating if statement.

Syntax

while (condition) {
  statements;
}

Flow Diagram:

In below mentioned example, program uses while loop to sum all integers from 1 to 5.

using System;
 
class MyProgram {
  static void Main(string[] args) {
    int i = 1;
    int sum = 0;
    while (i < 6){
        sum = sum + i;
        i = i+1;
    }
    Console.WriteLine(sum);
  }
}

The output of the above code will be:

The Do-While Loop

The Do-While loop in C# is a variant of while loop which execute statements before checking the conditions. Therefore the Do-While loop executes statements at least once.

Syntax

do {
  statements;
}
while (condition);

Flow Diagram:

In the example below, even if the condition is not fulfilled, the do-while loop executes the statements once.

using System;

class MyProgram {
  static void Main(string[] args) {
    int i = 10;
    int sum = 0;
    do{
      sum = sum + i;
      i = i+1;
    }
    while (i < 6);
    Console.WriteLine(sum); 
  }
}

The output of the above code will be: