来源：https://github.com/xg-wang/gobyexample/tree/master/examples

package main

import "fmt"

func main() {
    nums := []int{2, 3, 4}
    sum := 0
    for _, num := range nums {
        sum += num
    }
    fmt.Println("sum:", sum)

    //`range`在数组和slice中提供对每项的索引和值的访问
    for i, num := range nums {
        if num == 3 {
            fmt.Println("index:", i)
        }
    }

    kvs := map[string]string{"a": "apple", "b": "banana"}
    for k, v := range kvs {
        fmt.Printf("%s -> %s\n", k, v)
    }

    //`range`也可以只遍历map的键
    for k := range kvs {
        fmt.Println("key:", k)
    }

    //`range`在字符串中迭代 unicode码点(code point)
    //第一个返回值是字符的起始字节位置，然后第二个是字符本身
    for i, c := range "go" {
        fmt.Println(i, c)
    }
}

输出结果:

sum: 9
index: 1
b -> banana
a -> apple
key: a
key: b
0 103
1 111