如何使用动态 size/length/capacity 制作切片

Question

我似乎可以使用 size/capacity/length/whatever 创建动态切片：

cleaned := []interface{}{}

我怎样才能对 make() 做同样的事情？我试过这个：

cleaned := make([]interface{})

但它要我包括一个长度？

Missing len argument to make

Answer 1

你有两种方法：

使用 cleaned := make([]interface{},0) 然后调用 cleaned = append(cleaned, your_data)
正在声明一个空数组：var cleaned []interface{}{}

Answer 2

cleaned := []interface{}{}
how can I do the same with make()?

例如，

package main

import (
    "fmt"
)

func main() {
    {
        cleaned := []interface{}{}
        fmt.Println(len(cleaned), cap(cleaned), cleaned)
    }

    // OR

    {
        cleaned := make([]interface{}, 0)
        fmt.Println(len(cleaned), cap(cleaned), cleaned)
    }

    // OR

    {
        cleaned := make([]interface{}, 0, 0)
        fmt.Println(len(cleaned), cap(cleaned), cleaned)
    }
}

游乐场：https://play.golang.org/p/qndsxIKWjEp

输出：

0 0 []
0 0 []
0 0 []

参考：

The Go Programming Language Specification : Making slices, maps and channe

Comment: jetbrains complains and says Empty slice declaration via literal and suggests replacing with var cleaned []interface{} , but it's unclear why? – Olegzandr Denman

这是一个不同的问题。原因很清楚。

Go Code Review Comments : Declaring Empty Slices

When declaring an empty slice, prefer
var t []string
over
t := []string{}
The former declares a nil slice value, while the latter is non-nil but zero-length. They are functionally equivalent—their len and cap are both zero—but the nil slice is the preferred style.

. . .

例如，

package main

import (
    "fmt"
)

func main() {
    {
        cleaned := []interface{}{}
        fmt.Println(len(cleaned), cap(cleaned), cleaned, cleaned == nil)
    }

    // OR

    {
        cleaned := make([]interface{}, 0)
        fmt.Println(len(cleaned), cap(cleaned), cleaned, cleaned == nil)
    }

    // OR

    {
        cleaned := make([]interface{}, 0, 0)
        fmt.Println(len(cleaned), cap(cleaned), cleaned, cleaned == nil)
    }

    // OR

    {
        var cleaned []interface{}
        fmt.Println(len(cleaned), cap(cleaned), cleaned, cleaned == nil)
    }
}

游乐场：https://play.golang.org/p/9cZOOS2F9qI

输出：

0 0 [] false
0 0 [] false
0 0 [] false
0 0 [] true

如何使用动态 size/length/capacity 制作切片

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