go-map

package main import "fmt" /** 声明 var m map[int]string var b a := 赋值 map[int]string{} map[int]string{1: "a", 2: "b", 4: "c"} make(map[int]string) */ func main() { var m map[int]string m = map[int]string{} fmt.Println(m) var n map[int]string n = make(map[int]string) fmt.Println(n) var b = make(map[int]string) fmt.Println(b) a := make(map[int]string) fmt.Println(a) a[1] = "ok" fmt.Println(a) //输出map aa := a[1] fmt.Println(aa) //输出map的键对应的值 //复杂map-键对应也是map--使用map需要初始化 var x map[int]map[int]string x = make(map[int]map[int]string) x[1] = make(map[int]string) //键为1的map的键为1的值 x[1][1] = "ok" xx := x[1][1] yy := x[1][2] fmt.Println(xx) fmt.Println(yy) //空字符串 //p返回value,ok返回bool类型-键值对是否存在 p, ok := x[1][2] if !ok { x[1][2] = "aaa" p, ok = x[1][2] } fmt.Println(p, ok) fmt.Println("--------------迭代-----------------") //以map为类型的slice,长度为5 sm := make([]map[int]string, 5, 10) //迭代操作---索引、值 //得到的v是拷贝，不会对sm造成影响 for _, v := range sm { v = make(map[int]string, 2) v[1] = "ok1" v[2] = "ok2" fmt.Println(v) } fmt.Println(sm) fmt.Println("---------遍历切片类型的map集合,相当于foreach---------") smm := make([]map[int]string, 5) for iii := range smm { //smm[iii] = make(map[int]string) 这样也可以 smm[iii] = make(map[int]string, 1) smm[iii][1] = "aaaaaa" smm[iii][2] = "aaaddaaa" fmt.Println(smm[iii]) } fmt.Println(smm) fmt.Println("---------遍历map的键---------") r := map[int]string{1: "a", 2: "b", 4: "c"} //初始化一个map sortKey := make([]int, len(r)) //初始化一个存map键的切片 //遍历操作map-我需要的k，value不需要 i := 0 for k, _ := range r { sortKey[i] = k i++ } fmt.Println(sortKey) } map[] map[] map[] map[] map[1:ok] ok ok aaa true --------------迭代----------------- map[1:ok1 2:ok2] map[1:ok1 2:ok2] map[1:ok1 2:ok2] map[1:ok1 2:ok2] map[1:ok1 2:ok2] [map[] map[] map[] map[] map[]] ---------遍历切片类型的map集合,相当于foreach--------- map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[2:aaaddaaa 1:aaaaaa] [map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa] map[1:aaaaaa 2:aaaddaaa]] ---------遍历map的键--------- [1 2 4]