C# While Loop

The while Loop

A while loop checks a condition before each pass. If the condition is true, the code inside the curly braces runs. Then the condition is checked again, and this repeats until the condition becomes false. Each single pass through the loop body is called an iteration.

int i = 0;
while (i < 5)
{
    Console.WriteLine(i);
    i++;
}

In the example above, i starts at 0. As long as i is less than 5, the loop prints the value and then adds 1 to i with i++. Once i reaches 5, the condition i < 5 is false and the loop stops. The output is the numbers 0, 1, 2, 3, and 4.

The do/while Loop

The do/while loop is a variation that checks the condition at the end instead of the beginning. This guarantees the code block runs at least one time, even if the condition is false from the start.

int i = 0;
do
{
    Console.WriteLine("Value is: " + i);
    i++;
}
while (i < 3);

Use a plain while loop when it is okay to skip the body completely. Use do/while when the action must happen at least once, such as showing a menu before asking the user if they want to continue.