while Loop in Kotlin

The while Loop in Kotlin

What Is a while Loop?

A while loop in Kotlin is a control structure that repeats a block of code as long as a specified condition remains true. Each time the loop runs, it checks the condition before executing the code inside the loop. If the condition is false at the start, the loop body will not execute at all.

Basic Structure

A while loop uses the following syntax:

while (condition) {
    // Code to repeat
}

• The condition is a Boolean expression;
• The loop body runs only if the condition is true;
• The loop checks the condition before every repetition, including the first time.

When to Use a while Loop

Use a while loop when:

• You want to repeat an action until a certain condition changes;
• You do not know in advance how many times the loop should run;
• The number of repetitions depends on user input, random values, or other changing data.

Example: Repeating code until a user enters a specific value, or processing data until a list is empty.

When to Use while Loops

Use a while loop when you need to repeat a block of code as long as a specific condition is true. Unlike for loops, which are best for situations where you know exactly how many times you want to iterate, while loops are ideal when the number of iterations is not known in advance.

Typical Use Cases for while Loops

• Waiting for user input that meets certain criteria;
• Continuously reading data until the end of a file or stream is reached;
• Repeating an action until a variable reaches a specific value;
• Running a process until a resource becomes available;
• Implementing retry mechanisms where you do not know how many attempts will be needed.

while loops are especially useful when the loop's continuation depends on dynamic conditions that may change during execution. For example, you might use a while loop to prompt a user to enter a valid password, continuing to prompt until the user provides the correct input.