Basic Function Declaration
Let’s start with a basic function declaration. In Kotlin, functions are declared using the fun keyword.
fun greet() {
println("Hello, world!")
}
fun main() {
greet() // calls the function
}
In this example, we’ve defined a function called greet() that prints out a greeting. We then call this function in the main() function.
Function with Parameters
Functions can take parameters, which are values you supply to the function so it can perform a task.
fun greet(name: String) {
println("Hello, $name!")
}
fun main() {
greet("Kotlin") // calls the function with a parameter
}
Here, the greet() function takes a String parameter named name.
Function with Return Value
Functions can also return values. The return type of the function is defined after the parameters and is separated by a colon.
fun add(a: Int, b: Int): Int {
return a + b
}
fun main() {
val sum = add(2, 3)
println("Sum: $sum") // prints "Sum: 5"
}
In this example, the add() function takes two Int parameters and returns their sum, which is also an Int.
Advanced Functions
Now let’s delve into some more advanced function concepts in Kotlin.
Default Arguments
Kotlin allows you to specify default values for function parameters.
fun greet(name: String = "world") {
println("Hello, $name!")
}
fun main() {
greet() // prints "Hello, world!"
greet("Kotlin") // prints "Hello, Kotlin!"
}
If you call greet() without an argument, it uses the default value “world”.
Named Arguments
In Kotlin, you can use named arguments to make function calls more readable.
fun greet(greeting: String = "Hello", name: String = "world") {
println("$greeting, $name!")
}
fun main() {
greet(name = "Kotlin", greeting = "Goodbye") // prints "Goodbye, Kotlin!"
}
By using named arguments, we can specify the argument values by name, in any order.
Mastering functions is crucial to becoming proficient in Kotlin. They provide the means to create modular, reusable, and maintainable code. Always remember that learning a programming language is a continuous journey. Keep practicing and exploring the vast capabilities of Kotlin. You’re on your way to becoming a Kotlin pro!
