Kotlin While Loop

Welcome to The Coding College! In this tutorial, we will explore the while loop in Kotlin, a fundamental control structure for repetitive tasks in programming. By mastering loops, you can simplify your code and reduce redundancy.

What is a While Loop?

A while loop in Kotlin repeatedly executes a block of code as long as the given condition evaluates to true. It is commonly used when the number of iterations is unknown and depends on a condition being met.

Basic Syntax:

while (condition) {
    // Code to execute
}

How While Loops Work

1. The condition is evaluated before each iteration.
2. If the condition is true, the code block inside the loop is executed.
3. This process continues until the condition becomes false.

Example of a While Loop

Let’s look at a simple example to print numbers from 1 to 5:

fun main() {
    var number = 1
    while (number <= 5) {
        println(number)
        number++
    }
}

Output:

1  
2  
3  
4  
5  

Kotlin Infinite While Loop

A while loop without a condition that eventually becomes false can result in an infinite loop. Be cautious and ensure that the condition is properly managed.

Example:

fun main() {
    var count = 1
    while (true) {
        println("Count: $count")
        count++
        if (count > 5) break // Exit the loop
    }
}

Output:

Count: 1  
Count: 2  
Count: 3  
Count: 4  
Count: 5 

Kotlin While with User Input

You can use a while loop to process user input dynamically:

Example:

fun main() {
    var input: String
    do {
        println("Enter a word (type 'stop' to exit):")
        input = readLine() ?: ""
    } while (input != "stop")
    println("Program exited.")
}

The Do…While Loop

Kotlin also provides a do…while loop, which ensures that the code block runs at least once, even if the condition is false.

Syntax:

do {
    // Code to execute
} while (condition)

Example:

fun main() {
    var number = 1
    do {
        println(number)
        number++
    } while (number <= 5)
}

Output:

1  
2  
3  
4  
5 

Comparison: While vs Do…While

Practical Example: Factorial Using While Loop

Here’s an example of calculating the factorial of a number using a while loop:

fun main() {
    val num = 5
    var factorial = 1
    var i = 1
    while (i <= num) {
        factorial *= i
        i++
    }
    println("Factorial of $num is $factorial")
}

Output:

Factorial of 5 is 120

Best Practices for While Loops

1. Avoid Infinite Loops: Ensure the condition will eventually become false.
2. Update Loop Variables: Modify variables inside the loop to prevent endless execution.
3. Use Break Statements Wisely: Exit loops only when necessary and clearly indicate the reason.

Learn More on The Coding College

The while loop is a key component of any programming language. With its versatility, you can handle various repetitive tasks effectively. Visit The Coding College for more Kotlin tutorials, coding tips, and advanced programming concepts.

Conclusion

The while loop is an essential tool in Kotlin for controlling program flow. By understanding how to use while and do…while loops, you can write efficient, reusable code for a variety of tasks.