Calculate the size of the specified file type in the directory

main.go

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

func main() {
	if len(os.Args) < 2 {
		panic("usage: cal_size dir <filetype>")
	}
	dir := os.Args[1]
	var (
		size   int64
		filter string
	)
	if len(os.Args) == 3 {
		filter = os.Args[2]
	}
	err := filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if info.IsDir() {
			return nil
		}
		if strings.HasSuffix(path, filter) {
			size += info.Size()
		}
		return nil
	},
	)
	if err != nil {
		panic(err)
	}
	fmt.Printf("size: %d Bytes\n", size)
}