public/subjects/listforeach.md

# listpushback

## Instructions

Write a function `ListForEach` that applies a function given as argument to the information within each of the list's links.

- The function given as argument must have a pointer as argument: `l *list`

## Expected function and structure

```go
type Node struct {
	Data interface{}
	Next *Node
}

type List struct {
	Head *Node
	Tail *Node
}

func ListForEach(l *list, f func(l *list)) {
}
```

## Usage

Here is a possible [program](TODO-LINK) to test your function :

```go
package main

import (
	"fmt"
	piscine ".."
)

func main() {
	link := &List{}

	piscine.ListPushBack(link, 1)
	piscine.ListPushBack(link, 2)
	piscine.ListPushBack(link, 3)
	piscine.ListPushBack(link, 4)

	piscine.ListForEach(link, piscine.ListReverse)

	for link.Head != nil {
		fmt.Println(link.Head.Data)
		link.Head = link.Head.Next
	}
}
```

And its output :

```console
student@ubuntu:~/piscine/test$ go build
student@ubuntu:~/piscine/test$ ./test
4
3
2
1
student@ubuntu:~/piscine/test$
```