> For the complete documentation index, see [llms.txt](https://blog.yushunchen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blog.yushunchen.com/golang-notes/official-tutorial-notes/concurrency/range-and-close.md).

# Range and Close

A sender can `close` a channel to indicate that no more values will be sent. Receivers can test whether a channel has been closed by assigning a second parameter to the receive expression:

```go
v, ok := <-ch
```

`ok` is `false` if there are no more values to receive and the channel is closed.

The loop `for i := range c` receives values from the channel repeatedly until it is closed. Channels aren't like files, so they don't usually need to closed. Closing is only necessary when the receiver must be told there are no more values coming, such terminating the `range` loop.

### Example

```go
package main

import (
	"fmt"
)

func fibonacci(n int, c chan int) {
	x, y := 0, 1
	for i := 0; i < n; i++ {
		c <- x
		x, y = y, x+y
	}
	close(c)
}

func main() {
	c := make(chan int, 8)
	go fibonacci(cap(c), c)
	for i := range c {
		fmt.Println(i)
	}
}
```

```bash
0
1
1
2
3
5
8
13
```