57 lines
1.2 KiB
Markdown
57 lines
1.2 KiB
Markdown
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---
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title: Functions
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---
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# Functions
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### Basic Usage
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#### Declaration
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`fun` keyword is used to define the function
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`a` and `b` are input parameters of type `Int`
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`Int` (after brackets) is matching the return type
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```kotlin
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fun sum(a: Int, b: Int): Int {
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return a + b
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}
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```
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Same expression can be shortened (omit function brackets), meaning that return type is infered.
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Return keyword can be also omited in such expression body
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```kotlin
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fun sum(a: Int, b: Int) = a + b
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```
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Return type can also be omitted (you don't have to use `void` return type) if function does not return anything
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```kotlin
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fun printSum(a: Int, b: Int) {
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println("sum of $a and $b is ${a + b}")
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}
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```
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#### Usage
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Simple method call:
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```kotlin
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val result = sum(2, 3)
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```
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Named arguments in method call:
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```kotlin
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val result = sum(a = 1, b = 5)
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```
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Support of default arguments (if parameter is not provided in method call):
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```kotlin
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fun write(content: String, destination: String = "/tmp/") { ... }
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```
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#### Resources
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* [Basic Syntax Reference](https://kotlinlang.org/docs/reference/basic-syntax.html)
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* [Kotlin Functions Reference](https://kotlinlang.org/docs/reference/functions.html)
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