如何在golang中创建一个不固定的长度切片

Question

Is there any way to create a unfixed length slice in go? As a example, I want to grab all the fileNames in a directory(content/) fill to a [] string slice.

The content/ dir contains:

$-> tree content/
content/
├── 1.txt
├── 2.txt
└── tmp

Here is what I currently got:

package main

import (
    "fmt"
    "io/ioutil"
)

func listFile() []string {
    list := make([]string, 100)
    // as you can see, I make a slice length as 100, but that is not appropriate.

    files, _ := ioutil.ReadDir("content")
    i := 0
    for _, f := range files{
        list[i] = f.Name()
        i = i+1
    }
    return list
}

func main(){
    fmt.Print(listFile())
}

What I want to achieve is a way to simulate the behavior of ArrayList in java, which I can just simply list.add() and wont care about the length.

Can slice in GoLang do that?

Thanks.

Answer 1

A Go slice can't do that, but the append() function will grow your slice in a matter that appending elements becomes an O(1) amortized operation:

func listFile() []string {
    // make a slice of length 0
    list := make([]string, 0)

    files, _ := ioutil.ReadDir("content")
    for _, f := range files {
        // append grows list as needed
        list = append(list, f.Name())
    }

    return list
}