Go遍历struct,map,slice的实现
遍历结构体
如何实现遍历结构体字段? 好吧,言归正传!举个例子:
demo1:
package main import ( "fmt" "reflect" ) type Student struct { name string age int } func main() { v := reflect.ValueOf(Student{"乔峰", 29}) count := v.NumField() for i := 0; i < count; i++ { f := v.Field(i) //字段值 switch f.Kind() { case reflect.String: fmt.Println(f.String()) case reflect.Int: fmt.Println(f.Int()) } } }
再举给栗子:
package main import ( "fmt" "reflect" ) type LanType struct { s1, s2, s3 string } var language interface{} = LanType{"Php", "Go", "Python3"} func main() { value := reflect.ValueOf(language) for i := 0; i < value.NumField(); i++ { fmt.Printf("字段索引 %d: %v\n", i, value.Field(i)) } }
输出:
BASIC
字段索引 0: Php
字段索引 1: Go
字段索引 2: Python3
遍历切片
使用 for range遍历:
package main import ( "fmt" ) func main() { language := []string{"Php", "Go", "Python3"} for k, val := range language { fmt.Printf("切片索引 %d is :%s\n", k, val) } }
输出:
BASIC
切片索引 0 is :Php
切片索引 1 is :Go
切片索引 2 is :Python3
遍历Map
package main import ( "fmt" ) func main() { language := make(map[string]string) language["1"] = "Php" language["2"] = "Go" language["3"] = "Python3" language["4"] = "C#" for key, val := range language { fmt.Printf("%v=>%v\n", key, val) } }
输出:这里就不贴了,结果会随机输出,因为map遍历出来结果是无序的,顺序不好控制,也不利于业务逻辑;当业务依赖key次序时,那么我们就需要引入“sort”包来解决随机化问题:
比如这样:
package main import ( "fmt" "sort" ) func main() { language := make(map[string]string) language["1"] = "Php" language["2"] = "Go" language["3"] = "Python3" language["4"] = "C#" sorted_keys := make([]string, 0) for k, _ := range language { sorted_keys = append(sorted_keys, k) // 提取键名 } sort.Strings(sorted_keys) // for _, k := range sorted_keys { fmt.Printf("%v=>%v\n", k, language[k]) } }
输出:
BASIC
1=>Php
2=>Go
3=>Python3
4=>C#
这样输出的结果运行多次也不会改变顺序。
Golang json序列化(struct,int,map,slice)
package main import ( "encoding/json" "fmt" ) //把结构体都改小写 type User struct { UserName string `json:"user_name"` //json的tag标记 Nickname string `json:"nickname"` Age int Birthday string Sex string Email string Phone string } func testStruct() { user1 := &User{ UserName: "超哥", Nickname: "大头哥", Age: 18, Birthday: "2008/8/8", Sex: "男", Email: "mahuateng@qq.com", Phone: "110", } //开始json序列化 data, err := json.Marshal(user1) if err != nil { fmt.Printf("json.marshal failed,err:", err) return } fmt.Printf("%s\n", string(data)) } func testInt() { var a = 18 //开始json序列化 data, err := json.Marshal(a) if err != nil { fmt.Printf("json.marshal failed,err:", err) return } fmt.Printf("%s\n", string(data)) } func testMap() { var m map[string]interface{} //声明map m = make(map[string]interface{}) //必须初始化map分配内存 m["username"] = "user1" m["age"] = 18 m["sex"] = "man" fmt.Println(m) data, err := json.Marshal(m) if err != nil { fmt.Printf("json.marshal failed,err:", err) return } fmt.Printf("%s\n", string(data)) } func testSlice() { //定义一个slice,元素是map var m map[string]interface{} var s []map[string]interface{} m = make(map[string]interface{}) m["username"] = "user1" m["age"] = 18 m["sex"] = "man" s = append(s, m) m = make(map[string]interface{}) m["username"]="user2" m["age"]=188 m["sex"]="male" s=append(s,m) data, err := json.Marshal(s) if err != nil { fmt.Printf("json.marshal failed,err:", err) return } fmt.Printf("%s\n", string(data)) } func main() { testStruct() //结构体的序列化 testInt()//序列化数值 testMap()//序列化map testSlice()//序列化切片 }
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