Go中map的操作与使用(增删改查)

// code_014_map_operator project main.go
package main

import (
    "fmt"
)

func DeleteMap(m map[int]string, key int) {
    delete(m, key)
    for k, v := range m {
        fmt.Printf("len(m)=%d, %d ----> %s\n", len(m), k, v)
    }
}

func main() {
    //赋值-->修改和追加
    m1 := map[int]string{1: "ck_god", 2: "god_girl"}
    m1[1] = "xxx"
    m1[3] = "lily" //追加，go底层自动为map分配空间
    fmt.Println(m1)

    m2 := make(map[int]string, 10)
    m2[0] = "aaa"
    m2[1] = "bbb"
    fmt.Println(m2)
    fmt.Println(m2[0], m2[1])
    fmt.Println("")

    //遍历
    m3 := map[int]string{1: "ck_god", 2: "god_girl"}
    for k, v := range m3 {
        fmt.Printf("%d--->>>%s\n", k, v)
    }

    for k := range m3 {
        fmt.Printf("%d--->%s\n", k, m3[k])
    }
    fmt.Println("")

    //获取map的值
    value, ok := m3[1]
    fmt.Println("value = ", value, ", ok = ", ok)

    value2, ok2 := m3[3]
    fmt.Println("value2 = ", value2, ", ok2 = ", ok2)
    fmt.Println("")

    //删除
    m4 := map[int]string{1: "ck_god", 2: "god_girl"}
    delete(m4, 2) //删除key值为2的map
    for k, v := range m4 {
        fmt.Printf("%d--->%s\n", k, v)
    }
    fmt.Println("")

    //map作为参数传递
    //在函数间传递映射并不会制造出该映射的一个副本，不是值传递，而是引用传递：
    m := map[int]string{1: "ck_god", 2: "god_girl", 3: "girl_angle"}

    DeleteMap(m, 3)
    for k, v := range m {
        fmt.Printf("len(m)=%d, %d ----> %s\n", len(m), k, v)
    }
}

执行结果如下：

map[1:xxx 2:god_girl 3:lily]
map[1:bbb 0:aaa]
aaa bbb

1--->>>ck_god
2--->>>god_girl
2--->god_girl
1--->ck_god

value =  ck_god , ok =  true
value2 =   , ok2 =  false

1--->ck_god

len(m)=2, 1 ----> ck_god
len(m)=2, 2 ----> god_girl
len(m)=2, 1 ----> ck_god
len(m)=2, 2 ----> god_girl