申报片或制作片？ [英] Declare slice or make slice?

问题描述

在Golang中， var s [] int 和 s：= make（[] int，0）？

In Golang, what is the difference between var s []int and s := make([]int, 0)?

我发现这两种方法都有效，但哪一种更好？

I find that both works, but which one is better?

推荐答案

<除了 fabriziom 的 answer ，您可以在 Go Slices：usage和内部函数，其中提到了 [] int 的用法：

In addition to fabriziom's answer, you can see more examples at "Go Slices: usage and internals", where a use for []int is mentioned:

由于切片的零值（ nil ）的作用类似于零长切片，因此您可以声明切片变量，然后追加给它一个循环：

Since the zero value of a slice (nil) acts like a zero-length slice, you can declare a slice variable and then append to it in a loop:

// Filter returns a new slice holding only
// the elements of s that satisfy f()
func Filter(s []int, fn func(int) bool) []int {
    var p []int // == nil
    for _, v := range s {
        if fn(v) {
            p = append(p, v)
        }
    }
    return p
}

这意味着，要追加到一个片，您不必首先分配内存： nil 切片 p int [] 就足够作为切片添加到。

It means that, to append to a slice, you don't have to allocate memory first: the nil slice p int[] is enough as a slice to add to.

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