How to use C# do while loop

The while statement in C# allows for the execution of a single statement or a block of statements as long as a specified expression evaluates to true. It serves as a loop construct, repeatedly executing the associated code until the condition becomes false. This provides flexibility in controlling program flow based on dynamic conditions.

do..while loop

However, there are scenarios where you may want to ensure that the loop is executed at least once, even if the condition initially evaluates to false. This is where the do..while loop comes into play. This construct first executes the statements within the loop and then evaluates the specified condition. If the condition is true, the loop continues to execute, and if it becomes false, the loop terminates.

The do..while loop guarantees that the associated code block is executed at least once before checking the condition. This can be useful when you need to perform an initial action or validation before entering the loop.

From the following example you can understand how do..while loop function.

Full Source C#
using System; using System.Windows.Forms; namespace WindowsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { int count = 4; do{ MessageBox.Show(" Loop Executed "); count++; }while (count < =4); } } }

do..while loop VS. the while loop

The key distinction between the do..while loop and the while loop in C# lies in when the condition is evaluated. In a do..while loop, the condition is checked at the bottom of the loop after executing the statements within the loop block. As a result, the statements are always executed at least once, regardless of the initial evaluation of the condition.

This behavior is different from the while loop, where the condition is evaluated at the top of the loop. If the condition is initially false, the while loop will not execute the statements within the loop block.

The do..while loop is particularly useful when you need to ensure that a specific set of statements is executed at least once, regardless of the condition's initial evaluation. It provides a way to perform an initial action or validation before entering the loop, ensuring that the loop body executes at least once.


By using the while and do..while statements in your C# programs, you can create powerful loops that iterate until a condition is met, providing flexibility and control over the execution flow. These constructs offer efficient ways to handle repetitive tasks and make decisions based on changing conditions within your program.