golang for循环

package main

import "fmt"

func all() []int {
    fmt.Println("all running")
    return []int{1, 2, 3}
}

func main() {
    for {
        fmt.Printf("for\n")
        break
    }

    for i := 0; i < 10; i++ {
        fmt.Println(i)
    }

    vec := [5]int{4, 3, 2, 1}
    for k, v := range vec {
        fmt.Println(k, v)
    }

    str := "hello"
    for k, v := range str {
        fmt.Println(k, v)
    }

    for i := 1; i < len(str); i += 2 {
        fmt.Printf("%c%c", str[i-1], str[i])
    }

    fmt.Println()
    fmt.Printf("%d, %d\n", ('A'&0xdf-'A')+10, ('a'&0xdf-'A')+10)

    for _, v := range all() {
        fmt.Println(v)
    }
}