Go遍歷struct,map,slice

原文鏈接：http://www.zhoubotong.site/post/23.html

遍歷結構體

如何實現遍歷結構體字段? 好吧，言歸正傳!舉個例子：
demo1:

package main

import (
   "fmt"
   "reflect"
)

type Student struct {
   name string
   age  int
}

func main() {
   v := reflect.ValueOf(Student{"喬峯", 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())
      }
   }
}

再舉給栗子：

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))
   }
}

輸出：

BASIC

字段索引 0: Php
字段索引 1: Go
字段索引 2: Python3

遍歷切片

使用 for range遍歷：

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)
   }
}

輸出：

BASIC

切片索引 0 is :Php
切片索引 1 is :Go
切片索引 2 is :Python3

遍歷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)
   }
}

輸出：這裏就不貼了，結果會隨機輸出，因爲map遍歷出來結果是無序的，順序不好控制，也不利於業務邏輯;當業務依賴key次序時，那麼我們就需要引入“sort”包來解決隨機化問題：
比如這樣：

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) // 提取鍵名
   }
   sort.Strings(sorted_keys) //

   for _, k := range sorted_keys {
      fmt.Printf("%v=>%v\n", k, language[k])
   }
}

輸出：

BASIC

1=>Php
2=>Go
3=>Python3
4=>C#

這樣輸出的結果運行多次也不會改變順序。