Kotlin Single-Expression Function

Kotlin single-expression function is a function where a single expression is assigned to the function, and the expression’s evaluated value is returned when this function is called.

The syntax of Kotlin Single-Expression Function is

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fun functionName(parameters) = expression

The expression’s value is returned to the function call.

Examples

In the following Kotlin program, we write a single-expression function rectArea to compute the area of rectangle, given length and breadth as parameters.

Main.kt

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fun rectArea(length: Int, breadth: Int) = length * breadth

fun main(args: Array<String>) {
    val length = 5
    val breadth = 4
    val area = rectArea(length, breadth)
    print("Area of the rectangle is $area units.")
}

Output

Area of the rectangle is 20 units.

In the following Kotlin program, we write a single-expression function greet to return a greeting String.

Main.kt

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fun greet(name: String) = "Hello $name"

fun main(args: Array<String>) {
    val greeting = greet("Tesla")
    print(greeting)
}

Output

Hello Tesla

Conclusion

In this Kotlin Tutorial, we learned how to write a single-expression function in Kotlin, with the help of examples.