C# While Loops


What is Loop?

In programming, developers often require a repeated execution of a sequence of operations. A loop is a basic programming construct that allows repeated execution of a fragment of source code.

What is While Loops?

In a while loop, the code is repeated a fixed number of times or it repeats until a given condition is true.

while (condition)
{
    body loop;
}
  • The while statement executes a statement or a block of statements while a specified condition evaluates to true.
  • The condition is evaluated before each execution of the loop, a while loop executes zero or more times.

Example

Let's consider a very simple example of using the while loop.

// Initialize the counter
int counter = 0;

// Execute the loop body while the loop condition holds
while (counter <= 5)
{
    // Print the counter value
    Console.WriteLine("Number: " + counter);

    // Increment the counter
    counter++;
}

It will print the numbers in the range from 0 to 4 in ascending order on the console window.

Number: 0
Number: 1
Number: 2
Number: 3
Number: 4

What is do-while Loops?

The do-while loop is similar to the while loop, but it checks the condition after each execution of its body loop.

do
{
    executable code;
} 
while (condition);

The body of the do-while loop will execute at least once irrespective of the test-expression.

Example

Let's consider the same example of using the do-while loop.

// Initialize the counter
int counter = 0;

// Execute the do-while body loop
do
{
    // Print the counter value
    Console.WriteLine("Number: " + counter);

    // Increment the counter
    counter++;
}
while (counter <= 5);

It will print the numbers in the range from 0 to 5 in ascending order on the console window.

Number: 0
Number: 1
Number: 2
Number: 3
Number: 4
Number: 5

You can see that do-while is executed one more time and that is because the condition is checked after the body is executed, but in while loop, the condition is checked at the start.