负载因子6.5#
map引用传递#
map作为参数传递给函数时，是引用传递，引用传递类型还有slice和channel 函数对map的操作对原map变量是生效的
package main
import (
"fmt"
)
func main() {
m := make(map[string]string)
m["a"] = "a"
m["b"] = "b"
foo(m)
fmt.Printf("%+v", m) // output: map[a:b]
}
func foo(m map[string]string) {
m["a"] = "b"
delete(m, "b")
}
map[key]不可寻址#
package main
import "fmt"
type Student struct {
Name string
}
var list map[string]Student
func main() {
list = make(map[string]Student)
student := Student{"wwf"}
list["student"] = student
list["student"].Name = "wff"
fmt.Println(list["student"])
}
// Line 18: Char 23: cannot assign to struct field list["student"].Name in map (solution.go)
package main
import "fmt"
type Student struct {
Name string
}
var list []Student
func main() {
list = make([]Student, 1)
student := Student{"wwf"}
list[0] = student
list[0].Name = "wff"
fmt.Println(list[0])
}
package main
import (
"encoding/json"
"fmt"
)
func main() {
m := make(map[int]string)
m2 := make(map[int]string)
m[1] = "a"
m[2] = "b"
m2[2] = "c"
m2[3] = "d"
bs, _ := json.Marshal(m)
fmt.Println(string(bs)) // {"1":"a","2":"b"}
err := json.Unmarshal(bs, &m2)
if err != nil {
fmt.Println(err)
}
fmt.Printf("%+v\n", m2) // map[1:a 2:b 3:d]
}