get 6 random files from a directory

getSixRandomFiles.go

package main

import (
	"errors"
	"math/rand"
	"os"
	"time"
)

// initialize rng
func init() {
	rand.Seed(time.Now().UnixNano())
}

// reads all the file names in a dir and returns them
func getItems(dir string) ([]string, error) {
	files, err := os.ReadDir(dir)
	if err != nil {
		return nil, err // if read fails
	}
	items := make([]string, 0, len(files)) // init with expected capacity
	for _, f := range files {
		if !f.IsDir() { // only add files, ignore dirs
			items = append(items, f.Name())
		}
	}
	if len(items) > 0 {
		err = errors.New("no items")
	}
	return items, err
}

// shuffles strings using fisher-yates algo
func shuffle(arr []string) []string {
	newArr := make([]string, len(arr))
	copy(newArr, arr) // copy items to new array to shuffle
	for i := len(newArr) - 1; i > 0; i-- {
		j := rand.Intn(i + 1)
		newArr[i], newArr[j] = newArr[j], newArr[i]
	}
	return newArr
}

func main() {
	items, _ := getItems("./items")
	count := len(items)
	println("num items found:", count)
	println("\ninitial items:")
	for _, item := range items {
		println(item)
	}
	println("\n---------------------\n")
	shuffled := shuffle(items)
	first6 := shuffled[:6]
	println("first 6 items shuffled:")
	for _, item := range first6 {
		println(item)
	}
}