这是合理且惯用的GoLang循环移位实现吗？

Question

Can anyone comment on whether this is a reasonable and idiomatic way of implementing circular shift of integer arrays in Go? (I deliberately chose not to use bitwise operations.)

How could it be improved?

package main

import "fmt"

func main() {
    a := []int{1,2,3,4,5,6,7,8,9,10}
    fmt.Println(a)
    rotateR(a, 5)
    fmt.Println(a)
    rotateL(a, 5)
    fmt.Println(a)
}

func rotateL(a []int, i int) {
    for count := 1; count <= i; count++ {
        tmp := a[0]
        for n := 1;n < len(a);n++ {
            a[n-1] = a[n]
        }
        a[len(a)-1] = tmp
    }
}

func rotateR(a []int, i int) {
    for count := 1; count <= i; count++ {
        tmp := a[len(a)-1]
        for n := len(a)-2;n >=0 ;n-- {
            a[n+1] = a[n]
        }
        a[0] = tmp
    }
}

Answer 1

Your code is fine for in-place modification.

Don't clearly understand what you mean by bitwise operations. Maybe this

package main

    import "fmt"

    func main() {
        a := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
        fmt.Println(a)
        rotateR(&a, 4)
        fmt.Println(a)
        rotateL(&a, 4)
        fmt.Println(a)
    }

    func rotateL(a *[]int, i int) {
        x, b := (*a)[:i], (*a)[i:]
        *a = append(b, x...)
    }

    func rotateR(a *[]int, i int) {
        x, b := (*a)[:(len(*a)-i)], (*a)[(len(*a)-i):]
        *a = append(b, x...)
    }

Code works https://play.golang.org/p/0VtiRFQVl7

It's called reslicing in Go vocabulary. Tradeoff is coping and looping in your snippet vs dynamic allocation in this. It's your choice, but in case of shifting 10000 elements array by one position reslicing looks much cheaper.