golang map 获取某个值

package main

import "fmt"

func main() {

    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    fmt.Println("Geting values")
    courseName := m["a"]
}Copy

package main

import "fmt"

func main() {

    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    fmt.Println("Geting values")
    courseName := m["d"]
}Copy

package main

import "fmt"

func main() {

    m := map[string]int{
        "a": 1,
        "b": 2,
        "c": 3,
    }

    fmt.Println("Geting values")
    courseName, ok := m["a"]
    fmt.Println(courseName,ok)
    if courseName, ok := m["d"]; ok{
        fmt.Println(courseName)
    }else{
        fmt.Println("key does not exist")
    }
}Copy