Question

我正在尝试使用一个简单的模型来测试我对go频道的理解。在下面的小片段中，我尝试使用假新闻源的2个进程，将几个标题附加到本地数组，然后将其传递给数组字符串通道。在main中，我将这些数组传递回另一个打印过程。

编辑：我忘了提问题..我的问题是我一直得到'索引超出边界'异常而且我无法编译代码。

现在我用普通的字符串变量尝试了相同的代码并且它可以工作。

字符串数组代码：

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {

    /* initialization and assignment of channels */
    c := make(chan []string)
    p := make(chan []string)

    /* Pass created channels to Goroutines */
    go Feeder1(p)
    go Feeder2(p)
    go Consumer(c)

    for {
        select {
        case produced := <-p:
            c <- produced
        /*case <-time.After(6 * time.Second):
        return*/
        default:
            fmt.Printf("\n --- We timed out! --- \n")
            time.Sleep(5 * time.Second)

        }
    }
}

func Feeder2(w chan []string) {

    headlines := []string{
        "BBC: Speedboat victim 'doted on family'\n",
        "BBC: Syria rebel sarin claim downplayed\n",
        "BBC: German 'ex-Auschwitz guard' arrested\n",
        "BBC: Armless artist 'denied entry' to UK\n",
        "BBC: Bangladesh protest clashes kill 27\n",
        "BBC: Ex-Italian PM Giulio Andreotti dies\n"}

    for i := 0; ; i++ {
        selection := []string{}
        for s := 0; s <= 3; s++ {
            selection[s] = headlines[randInt(0, len(headlines))]
        }
        w <- selection
        time.Sleep(5 * time.Second)
    }
}

func Feeder1(w chan []string) {

    headlines := []string{
        "SKY: Deadly Virus Can 'Spread Between People'\n",
        "SKY: Ariel Castro's Brothers Brand Him 'A Monster'\n",
        "SKY: Astronaut Ends Space Mission With Bowie Song\n",
        "SKY: Chinese Artist Films Violent Street Brawl\n",
        "SKY: May Washout: Fortnight's Rainfall In One Day\n",
        "SKY: Mother's Day Shooting: CCTV Shows Suspect\n"}

    for i := 0; ; i++ {
        selection := []string{}
        for q := 0; q <= 3; q++ {
            selection[q] = headlines[randInt(0, len(headlines))]
        }
        w <- selection
        //randomTimeValue := randInt(5, 6)
        time.Sleep(2 * time.Second)
    }
}

func Consumer(n chan []string) {

    for {
        v := <-n
        for _, x := range v {
            fmt.Printf("Headline:\t%s", x)
        }
    }
}

func randInt(min int, max int) int {
    return min + rand.Intn(max-min)
}

以前运行的代码版本（此处没有数组）：

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {

    /* initialization and assignment of channels */
    c := make(chan string)
    p := make(chan string)

    /* Pass created channels to Goroutines */
    go Feeder1(p)
    go Feeder2(p)
    go Consumer(c)

    for {
        select {

        case produced := <-p:
            c <- produced
        /*case <-time.After(6 * time.Second):
        return*/
        default:
            fmt.Printf("\n --- We timed out! --- \n")
            time.Sleep(5 * time.Second)

        }
    }
}

func Feeder2(w chan string) {
    headlines := []string{
        "BBC: Speedboat victim 'doted on family'\n",
        "BBC: Syria rebel sarin claim downplayed\n",
        "BBC: German 'ex-Auschwitz guard' arrested\n",
        "BBC: Armless artist 'denied entry' to UK\n",
        "BBC: Bangladesh protest clashes kill 27\n",
        "BBC: Ex-Italian PM Giulio Andreotti dies\n"}

    for i := 0; ; i++ {
        w <- headlines[randInt(0, len(headlines))]
        time.Sleep(5 * time.Second)
    }
}

func Feeder1(w chan string) {
    headlines := []string{
        "SKY: Deadly Virus Can 'Spread Between People'\n",
        "SKY: Ariel Castro's Brothers Brand Him 'A Monster'\n",
        "SKY: Astronaut Ends Space Mission With Bowie Song\n",
        "SKY: Chinese Artist Films Violent Street Brawl\n",
        "SKY: May Washout: Fortnight's Rainfall In One Day\n",
        "SKY: Mother's Day Shooting: CCTV Shows Suspect\n"}

    for i := 0; ; i++ {
        w <- headlines[randInt(0, len(headlines))]
        //randomTimeValue := randInt(5, 6)
        time.Sleep(2 * time.Second)
    }
}

func Consumer(n chan string) {

    for {
        v := <-n
        fmt.Printf("Headline:\t%s", v)
    }
}

func randInt(min int, max int) int {
    return min + rand.Intn(max-min)
}

这两个版本都不适用于游乐场网站。

谢谢

Answer 1

你的问题在这里：

selection := []string{}
for s := 0; s <= 3; s++ {
    selection[s] = headlines[randInt(0, len(headlines))]
}

selection是一个长度为0的片段。当您尝试将值设置为索引0,1和2时 - 这会导致运行时错误，因为没有为它们分配空间。< / p>

初始化切片的首选方法是使用make()：

selection := make([]string, 3, 3)
for s := 0; s <= 3; s++ {
    selection[s] = headlines[randInt(0, len(headlines))]
}

make()的第三个参数是容量。

另一种可能性是让运行时使用append()隐式增加切片：

selection := []string{}
for s := 0; s <= 3; s++ {
    selection = append(selection, headlines[randInt(0, len(headlines))])
}

append()会根据需要增加一个切片。

Link to relevant documentation

Answer 2

您的字符串“数组”代码使用切片，而不是数组。你正在做选择[q] =某事，但你的切片长度为0，应该恐慌。要么：做得好切片用len！= 0或者使用数组。

（我个人更喜欢游乐场代码）。

与类型数组的通道通信

2 个答案: