Go 语言Map(集合)

定义 Map

/* 声明变量，默认 map 是 nil */
var map_variable map[key_data_type]value_data_type

/* 使用 make 函数 */
map_variable = make(map[key_data_type]value_data_type)

 

package main

import "fmt"

func main() {
var countryCapitalMap map[string]string
/* 创建集合 */
countryCapitalMap = make(map[string]string)

/* map 插入 key-value 对，各个国家对应的首都 */
countryCapitalMap["France"] = "Paris"
countryCapitalMap["Italy"] = "Rome"
countryCapitalMap["Japan"] = "Tokyo"
countryCapitalMap["India"] = "New Delhi"

/* 使用 key 输出 map 值 */
for country := range countryCapitalMap {
fmt.Println("Capital of",country,"is",countryCapitalMap[country])
}

/* 查看元素在集合中是否存在 */
captial, ok := countryCapitalMap["United States"]
/* 如果 ok 是 true, 则存在，否则不存在 */
if(ok){
fmt.Println("Capital of United States is", captial)
}else {
fmt.Println("Capital of United States is not present")
}
}

 

delete() 函数

package main

import "fmt"

func main() {
/* 创建 map */
countryCapitalMap := map[string] string {"France":"Paris","Italy":"Rome","Japan":"Tokyo","India":"New Delhi"}

fmt.Println("原始 map")

/* 打印 map */
for country := range countryCapitalMap {
fmt.Println("Capital of",country,"is",countryCapitalMap[country])
}

/* 删除元素 */
delete(countryCapitalMap,"France");
fmt.Println("Entry for France is deleted")

fmt.Println("删除元素后 map")

/* 打印 map */
for country := range countryCapitalMap {
fmt.Println("Capital of",country,"is",countryCapitalMap[country])
}
}