Self study golang [3.7map exercise code]

map Practice code for ：

package main

import "fmt"

func main() {
	m := map[string]string{ // Define a map
		"name":    "lwj",
		"course":  "golang",
		"site":    "im",
		"quality": "good",
	}
	m2 := make(map[string]int) // Define an empty map.m2==empty map
	var m3 map[string]int      // Define an empty map, Same as m2 equally .m3==nil
	fmt.Println(m, m2, m3)
	fmt.Println("map The traversal :")
	for k, v := range m { // The order of output is out of order 
		fmt.Println(k, v)
	}
	fmt.Println(" obtain map A variable value of :")
	coursename := m["course"] //course If the input is wrong, a blank will be output 
	fmt.Println(coursename)
	// Prevent the variable value from nonexistence 
	if causename, ok := m["cause"]; ok { // Judge whether the value exists 
		fmt.Println(causename)
	} else {
		fmt.Println(" Keywords don't exist ")
	}
	fmt.Println(" Delete map A variable value of :")
	name, ok := m["name"]
	fmt.Println(name, ok)
	delete(m, "name")
	name, ok = m["name"]
	fmt.Println(name, ok)
}

Running results ：

map The traversal :          
course golang       
site im             
quality good        
name lwj            
 obtain map A variable value of :
golang              
 Keywords don't exist         
 Delete map A variable value of :
lwj true            
 false