编辑代码

package main
import "fmt"
func main () {
    // test for map
    res := map[string]float64{
        "a": 1,
        "b": 2,
    }
    a, _ := res["a"]
    c, _ := res["c"]  // c=0, c是对应类型的默认值
    fmt.Println("a: ", a)
    fmt.Println("c: ", c)
}