Go - 范围

range关键字在for循环中用于迭代数组、切片、通道或映射的项。对于数组和切片，它以整数形式返回项的索引。对于映射，它返回下一个键值对的键。范围返回一个值或两个值。如果在范围表达式的左侧仅使用一个值，则它是下表中的第一个值。

Example

The following paragraph shows how to use range −

package main

import "fmt"

func main() {
   /* create a spce */
   numbers := []int{0,1,2,3,4,5,6,7,8} 
   
   /* print the numbers */
   for i:= range numbers {
      fmt.Println("Spce item",i,"is",numbers[i])
   }
   
   /* create a map*/
   countryCapitalMap := map[string] string {"France":"Paris","Italy":"Rome","Japan":"Tokyo"}
   
   /* print map using keys*/
   for country := range countryCapitalMap {
      fmt.Println("Capital of",country,"is",countryCapitalMap[country])
   }
   
   /* print map using key-value*/
   for country,capital := range countryCapitalMap {
      fmt.Println("Capital of",country,"is",capital)
   }
}

When the above code is compiled and executed, it produces the following result −

Spce item 0 is 0
Spce item 1 is 1
Spce item 2 is 2
Spce item 3 is 3
Spce item 4 is 4
Spce item 5 is 5
Spce item 6 is 6
Spce item 7 is 7
Spce item 8 is 8
Capital of France is Paris
Capital of Italy is Rome
Capital of Japan is Tokyo
Capital of France is Paris
Capital of Italy is Rome
Capital of Japan is Tokyo