How many times must a channel be closed in Go to avoid errors?

In Go, a channel must be closed exactly once, when no more data is expected to be sent to it. Closing a channel multiple times will cause a panic (runtime panic).

Important:

• The channel should be closed by the sender, not the receiver.
• If the channel is used for data transfer between goroutines, closing it signals that no more data will be sent.

Example:

ch := make(chan int)
go func() {
    defer close(ch) // close the channel once
    for i := 0; i < 5; i++ {
        ch <- i
    }
}()

for val := range ch {
    fmt.Println(val)
}

In this example, the channel is closed once after all values are sent.