Summary - Functions
- Go course
- Beginner
- Lesson 34/90
- 4 min
Use multiple return and variadic parameters to write a helper.
Functions summary
In this group you learned the func name(parameters) result syntax, pass by value, multiple returns like (result, error), named returns, variadic parameters with ..., anonymous functions and closures.
func uygula(s []int, f func(int) int) []int {
sonuc := make([]int, len(s))
for i, v := range s {
sonuc[i] = f(v)
}
return sonuc
}Functions that take functions (higher-order) gather repeated loops in one place.
defer
defer postpones a call until the function ends; several defers run in reverse order (last in, first out). It's used for cleanup such as closing files and unlocking:
func islem() {
defer fmt.Println("bitti")
fmt.Println("çalışıyor")
}
// çalışıyor
// bittiA defer's arguments are evaluated when the defer line runs; the call itself happens at the end.
Practice Higher-order function
Write the uygula function above. Print the result of uygula([]int{1, 2, 3}, func(n int) int { return n * n }).
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
func uygula(s []int, f func(int) int) []int {
sonuc := make([]int, len(s))
for i, v := range s {
sonuc[i] = f(v)
}
return sonuc
}
func main() {
fmt.Println(uygula([]int{1, 2, 3}, func(n int) int { return n * n }))
}Expected output
[1 4 9]
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does <code>uygula([]int{1, 2}, func(n int) int { return n + 10 })</code> return?
- [11 12] Correct answer
- [1 2]
- 23
- [10 10]
Explanation: uygula applies the given function to every element: 1+10, 2+10.
2 Postpone
func oku() {
____ fmt.Println("dosya kapandı")
fmt.Println("okunuyor")
}func oku() {
defer fmt.Println("dosya kapandı")
fmt.Println("okunuyor")
}Explanation: defer postpones the call to the end of the function.
3 Group summary
| Term | Meaning |
|---|---|
func ... |
Definition |
(int, error) |
Multiple returns |
...int |
Variadic |
defer |
Postponing to the end |