golang-101-hacks(9)——追加元素

注:本文是对golang-101-hacks中文翻译。 在Slice中添加元素:可以使用“Go”内置函数append Go has a built-in append function which add elements in the slice:

func append(slice []Type, elems ...Type) []Type

但是如果需要增加到最前面,可以使用copy函数,如下 But how if we want to the "prepend" effect? Maybe we should use copy function. E.g.:

package main

import "fmt"

func main()  {
    var s []int = []int{1, 2}
    fmt.Println(s)

    s1 := make([]int, len(s) + 1)
    s1[0] = 0
    copy(s1[1:], s)
    s = s1
    fmt.Println(s)

} 

运行结果 The result is like this:

[1 2]
[0 1 2]

上面的代码看上去不是很完美,一种友好的写法如下 But the above code looks ugly and cumbersome, so an elegant implementation maybe here:

s = append([]int{0}, s...)

顺便补充一点,我尝试写了一个通用的前置增加函数 BTW, I also have tried to write a "general-purpose" prepend:

func Prepend(v interface{}, slice []interface{}) []interface{}{
    return append([]interface{}{v}, slice...)
}

但是由于[]T不能直接转换成[]interface{}(请参考https://golang.org/doc/faq#convert_slice_of_interface,因此也就是玩玩啦,没什么实际意义。 But since []T can't convert to an []interface{} directly (please refer https://golang.org/doc/faq#convert_slice_of_interface, it is just a toy, not useful.

参考:: Go – append/prepend item into slice.

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