go语言map操作

package main

import "fmt"

func main() {
	var m = map[int]string{
		90: "优秀",
		80: "良好",
		60: "及格", //逗号不能省略，会报错
	}

	//遍历map中的元素
	for k, v := range m {
		fmt.Println(k, v)
	}

	for s := range m {
		fmt.Println(s)
	}
	
	//读取某个值
	var score = m[90]
	fmt.Println(score)

	//map 中增加一项
	m[70] = "中等"
	fmt.Println(m)

	//map 删除一项
	delete(m, 60)
	fmt.Println(m)

	fmt.Println(m, len(m))
}