map

map

代码

//example.go
package test

import "fmt"

//map是无序的键值对映射
func Map() {
	//key:string value:string
	var m1 map[string]string
	//通过make给map分配空间，默认map空间为1，会自动增长
	m1 = make(map[string]string) //make(Type,初始size) 注意：初始size可以省略，默认为1
	m1["早上"] = "敲代码"
	m1["中午"] = "送外卖"
	m1["晚上"] = "开滴滴"
	fmt.Println("m1 = ", m1)
	//第二种声明方式
	m2 := map[string]string{
		"下午": "123",
		"凌晨": "456",
	}
	fmt.Println("m2 =", m2)
	//判断map中是否存在值
	v, ok := m2["早上"]
	if ok {
		fmt.Println("v = ", v)
	} else {
		fmt.Println("key不存在")
	}
	//删除map中元素
	delete(m1, "晚上")
	fmt.Println("m1 = ", m1) //m1 =  map[中午:送外卖 早上:敲代码]
	//清空map
	//1.	赋值为nil
	//2.	重新make
	//m1 = nil
	m2 = make(map[string]string)
	fmt.Println("m2 =", m2)

	//map的遍历，只能用for...range,len()不适用于map
	for key, value := range m1 {
		fmt.Printf("key = %v,value = %v\n", key, value)
	}
}

//main.go
package main

import "GoExample/test"

func main() {
	test.Map()
}

	本博客参考自：
		https://www.bilibili.com/video/BV1s341147US/?spm_id_from=333.337.search-card.all.click&vd_source=a642bb3ddc5b706845426dc41d73fbda