在Go中打印频道内容

Question

How can I print the contents of a channel in Go?

For example:

package main

import "fmt"

func main() {
    ok := make(chan int)
    ok <- 1
    x := <- ok
    fmt.Println(x)
}

As I understand, ok is a channel which can store an integer value. So, how can I print its contents?

fmt.Println(ok) doesn't print the value stored inside the channel.

Thanks.

Answer 1

Channels make(chan int) has implicit size zero ( ref: https://golang.org/ref/spec#Making_slices_maps_and_channels)

A channel of size zero is unbuffered. A channel of specified size make(chan int, n) is buffered. See http://golang.org/ref/spec#Send_statements for a discussion on buffered vs. unbuffered channels. The example at http://play.golang.org/p/VZAiN1V8-P illustrates the difference.

Here, channel <-ok or ok <- will be blocked until someone processes it (concurrently). So, change ok := make(chan int) to ok := make(chan int,1)

package main

import "fmt"

func main() {
    ok := make(chan int, 1)
    ok <- 1
    x := <- ok
    fmt.Println(x)
}

Or concurrently proccess it

package main

import "fmt"

func main() {
    ok := make(chan int)
    go func(){
       ok <- 1
    }()
    x := <- ok
    fmt.Println(x)
}