Question

我正在尝试使用此处的删除示例从切片中删除多个项目：http://code.google.com/p/go-wiki/wiki/SliceTricks 这是我的代码：

package main

import "fmt"
import "net"

func main() {
    a := []string{"72.14.191.202", "69.164.200.202", "72.14.180.202", "2600:3c00::22", "2600:3c00::32", "2600:3c00::12"}
    fmt.Println(a)
    for index, element := range a {
        if net.ParseIP(element).To4() == nil {
            //a = append(a[:index], a[index+1:]...)
            a = a[:index+copy(a[index:], a[index+1:])]
        }
    }
    fmt.Println(a)
}

虽然如果切片中只有一个IPv6地址，但代码工作正常，但如果有多个IPv6地址则会失败。它失败并显示错误“panic：runtime error：slice bounds out of range”。我该怎么做才能修复此代码，以便能够删除所有IPv6地址？

Answer 1

您的问题是您正在修改正在迭代的切片。下面是你的代码有点修改：

package main

import (
    "fmt"
    "net"
)

func main() {
    a := []string{"72.14.191.202", "69.164.200.202", "72.14.180.202", "2600:3c00::22", "2600:3c00::32", "2600:3c00::12"}
    fmt.Println(a)
    for i := 0; i < len(a); i++ {
        if net.ParseIP(a[i]).To4() == nil {
            a = append(a[:i], a[i+1:]...)
            //a = a[:i+copy(a[i:], a[i+1:])]
            i-- // Since we just deleted a[i], we must redo that index
        }
    }
    fmt.Println(a)
}

Playground

Answer 2

提出要点：改变你正在迭代的结构总是很棘手避免这种情况的常见方法是在新变量中构建最终结果：

package main

import (
    "fmt"
    "net"
)

func main() {
    a := []string{"72.14.191.202", "69.164.200.202", "72.14.180.202", "2600:3c00::22", "2600:3c00::32", "2600:3c00::12"}
    fmt.Println(a)

    var b []string
    for _, ip := range a {
        if net.ParseIP(ip).To4() != nil {
                b = append(b, ip)
        }
    }
    fmt.Println(b)
}

http://play.golang.org/p/7CLMPw_FQi

从切片中删除多个项目

2 个答案: