Using Ranges in When

Using Ranges in When in Kotlin

Kotlin lets you use ranges in a when expression to check if a value is within a specific sequence of numbers or characters. This makes your code cleaner and easier to read than using multiple comparisons.

What Is a Range?

A range in Kotlin is a sequence of values with a start and an end, such as 1..10 for numbers or 'a'..'z' for characters. You can use the in keyword to check if a value belongs to a range.

Why Use Ranges in When?

• Simplifies checking if a value is between two limits;
• Makes code more readable and concise;
• Reduces the need for multiple logical conditions.

Basic Syntax

when (value) {
    in 1..10 -> println("Value is between 1 and 10")
    !in 11..20 -> println("Value is not between 11 and 20")
    else -> println("Value is something else")
}

Typical Use Cases

• Checking if a user's age is within a valid range;
• Grouping scores into letter grades;
• Validating if a character is a letter or digit.

Using ranges in when expressions helps you write safer, more expressive code when working with intervals.