douguadao3883
2015-10-25 01:59 阅读 88
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Golang中=和<-有什么区别

func worker(id int, jobs <-chan int, results chan<- int) {
    for j := range jobs {
        fmt.Println("worker", id, "processing job", j)
        time.Sleep(time.Second)
        results <- j * 2
    }
}

func main() {
    t := time.Now()
    fmt.Println(t)
    jobs := make(chan int, 100)
    results := make(chan int, 100)
    for w := 1; w <= 4; w++ {
        go worker(w, jobs, results)
    }
    for j := 1; j <= 20; j++ {
        jobs <- j
    }
    close(jobs)
    for a := 1; a <= 20; a++ {
        <-results
    }

    t = time.Now()
    fmt.Println(t)
}

I am confused of the "<-" and I can not find any related documents about "<-". So what is the difference between <- and =?? why I can not use = here?

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3条回答 默认 最新

  • 已采纳
    douliangpo0128 douliangpo0128 2015-10-25 02:16

    This is related to channels in Go. You are thinking it's related to assignment as in other languages. In your code, a value "j" is being sent to the channel "jobs".

    https://gobyexample.com/channels

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  • dtudj42064 dtudj42064 2015-10-25 03:13
    • "=" is assignment,just like other language.
    • <- is a operator only work with channel,it means put or get a message from a channel.
    • channel is an important concept in go,especially in concurrent programming.you can try this Channel TourPage to see its using scene.
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  • dstbtam8732 dstbtam8732 2015-10-25 03:14

    The = operator deals with variable assignment as in most languages. It expresses the idea of wanting to update the value that an identifier references. The <- operator represents the idea of passing a value from a channel to a reference. If you think of the channel as a queue using an assignment operator = would assign the reference to the queue to the target variable. The receive operator <- is equivalent to dequeuing from the queue and assigning the value of the item to the target variable.

    You cannot use the operators interchangeably because of a type mismatch. Please note the links to the Go specification which speak at greater length to the operators.

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