/
main.go
64 lines (54 loc) · 868 Bytes
/
main.go
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package main
import "fmt"
func main() {
//map1()
//map2()
//map3()
map4()
}
func map1() {
m := make(map[int]string)
m[1] = "h"
m[2] = "w"
fmt.Println(m)
for k := range m {
//fmt.Println(k)
m[k] = "k"
}
fmt.Println(m)
}
func map2() {
m := make(map[int]string)
m[1] = "h"
m[5] = "w"
fmt.Println(m)
for i := 0; i < len(m); i++ {
m[i] = "k"
}
fmt.Println(m)
}
func map3() {
m := make(map[int]int)
for i := 0; i < 10; i++ {
m[i] = i
}
for k := range m {
delete(m, k)
}
m = nil
}
func map4() {
//var m map[string]int
//m["one"] = 1
//fmt.Println(m)
m := make(map[int]int)
m[1] = 1
v1, ok := m[1]
fmt.Println(v1, ok) // 1, true
v2 := m[1]
fmt.Println(v2) // 1
v3, ok := m[2]
fmt.Println(v3, ok) // 返回类型默认值和false
v4 := m[2]
fmt.Println(v4) // 返回类型默认值,这里不小心也很容易犯错
}