Go language first taste

This is a creation in Article, where the information may have evolved or changed.

The only thing to keep in mind when it comes to language design is that C becomes C + +.

Go is a lightweight and concise support for concurrent languages that can be used for exploratory personal projects, which is the main reason I want to learn this language. For someone with some programming experience, the way to learn a new language is to take a glance at the language features and then write a medium-sized program that uses as much of the most important features as possible.

The following program is used to calculate the size of all files or directories in a directory.

Package Mainimport ("FMT" "Time" "OS" "Log") type shortfileinfo struct {fileName stringsize int64}func (fileInfo *shortfileinfo) Desc () string {return FMT. Sprintf ("{%s:%d}", Fileinfo.filename, Fileinfo.size)}func producefiles (DirName string) []os. FileInfo {path, err: = OS. Open (dirName) if err! = Nil {log. Fatal (ERR)} defer path. Close () Fileinfos, err: = path. Readdir (0); if err! = Nil {log. Fatal (Err)} return Fileinfos;} Func procFile (FileInfo os. FileInfo, basedirname string, Channelbuffer chan shortfileinfo) {var filesize int64filename: = Fileinfo.name () if FileInfo . Isdir () {filesize = Totalfilesizeindir (FileInfo, Basedirname)} else {filesize = Fileinfo.size ()} shortfileinfo: = S Hortfileinfo{filename, Filesize};fmt. Println (time. Now (). String () + "store:" + shortfileinfo.desc ()) Channelbuffer <-shortfileinfo}func totalfilesizeindir (fileInfo os. FileInfo, basedirname String) Int64 {var filesize int64 = 0fileInfos: = Producefiles (BasedirnaMe + "\ \" + fileinfo.name ()) for _, Subfileinfo: = Range Fileinfos {if Subfileinfo.isdir () {filesize + = Totalfilesizeindir ( Subfileinfo, basedirname + "\ \" + Fileinfo.name ())} else {filesize + = Subfileinfo.size ()}}return Filesize}func sleep (ns in T) {time. Sleep (time. Duration (time. Second) *time. Duration (NS))}const (B int64 = 1KB Int64 = 1024MB Int64 = 1024*1024GB Int64 = 1024*1024*1024TB Int64 = 1024*1024*1024*1024 ) Const FORMATF string = "%8.4f" func readablesize (sizeinbytes Int64) string {switch {case B <= sizeinbytes && s Izeinbytes < Kb:return FMT. Sprintf ("%db", sizeinbytes) case KB <= sizeinbytes && sizeinbytes < Mb:return FMT. Sprintf (formatf+ "KB", Float64 (sizeinbytes)/float64 (KB)) Case MB <= sizeinbytes && sizeinbytes < Gb:return Fmt. Sprintf (formatf+ "MB", Float64 (sizeinbytes)/float64 (MB)) Case GB <= sizeinbytes && sizeinbytes < Tb:return Fmt. Sprintf (formatf+ "GB", Float64 (sizeinbytes)/float64 (GB)) Case TB <= Sizeinbytes:return FMT. Sprintf (formatf+ "TB", Float64 (sizeinbytes)/float64 (TB)) default:return "0"}}func main () {basedirname: = "C:\\users\\qin . Shuq\\desktop "FileList: = Producefiles (basedirname) FileNumber: = Len (fileList) Channelbuffer: = Make (chan        Shortfileinfo, filenumber) Fileinfomap: = Make (Map[string] int64, filenumber) for _, FileInfo: = Range FileList { Go ProcFile (FileInfo, Basedirname, Channelbuffer)} for Count: = 0; Count <= FileNumber; {select {case fileInfo: = <-channelbuffer:fmt. Println (time. Now (). String () + "Fetch:" + FILEINFO.DESC ()) Fileinfomap[fileinfo.filename] = fileinfo.sizecount++default:if Count = = Filenumb ER {close (channelbuffer)}fmt.  Println ("Waiting for data ...") Sleep (2)}}var totalsize Int64 totalsize = 0for _, FileSize: = Range Fileinfomap {totalsize + = Filesize}fmt.  Printf ("Total size in%s:%db%s", Basedirname, TotalSize, Readablesize (TotalSize));}