How to Close a Channel in Go (And Why It Matters)

Close a Go channel by calling close(ch) on the sender side to signal that no more values will be sent. Closing a channel prevents further sends (which would panic) and allows receivers to detect when the stream is finished via the ok value in the receive operation.

ch := make(chan int)

// Sender: send values then close
for i := 0; i < 5; i++ {
    ch <- i
}
close(ch)

// Receiver: read until closed
for val := range ch {
    fmt.Println(val)
}
// Loop exits automatically when ch is closed

Closing matters because it provides a clean way to signal completion in concurrent programs, allowing goroutines to exit loops gracefully without needing separate stop signals or timeouts.

Closing a channel in Go is like putting a 'closed' sign on a delivery pipe. It tells everyone listening that no more items are coming, so they can stop waiting and move on. This prevents programs from getting stuck forever waiting for data that will never arrive.