Hello Zachary Stdin and os.Args are quite different. If your wrote a go program named "kaplan", then when running the following command on a unix-like system (linux, or OSX) :
cat bigphoto.jpg | kaplan sepia downscale > result.jpg you have os.Args[0]=="kaplan", os.Args[1]=="sepia", os.Args[2]=="downscale". They are all strings indeed, but it is unlikely that using them will cause any inefficiency, because the total length of the command-line arguments is usually small (<1000). you also have all the bytes from the contents of the file "bigphoto.jpg" streamed to the os.Stdin of your program. os.Stdin is a os.File, which implements io.Reader. It is designed to handle bytes, not strings. More precisely, you would call os.Stdin.Read to put the bytes into the []byte of your choice. If your func : - wants to return a short, human-readable text: return a string. - wants to build a long and immutable human-redable text: make a buf []byte, fill it, then return string(buf). - wants to return binary data: return a []byte. - wants to return text data that the caller will modify: return a []byte. Also, you may find interesting (for efficiency) that reslicing a substring doesn't create a copy : t := s[30:55] t shares the same immutable array in memory as s. See video Lexical Scanning in Go <https://www.youtube.com/watch?v=HxaD_trXwRE> : the whole lexer may parse the input file as one big string, without ever copying the tokens characters : tokens are just "slices" of the source code. HTH, Val On Wednesday, May 10, 2017 at 7:15:01 PM UTC+2, Zachary Kaplan wrote: > > in golang, strings are immutable. thus, if i want to modify a string in > place, i'll need to cast or copy each element from the string to a similar > but mutable data structure. this seems inefficient for simple command line > programs that take input from stdin and access it through os.Args. can > somebody please explain to me when a function should to return a string as > opposed to, say a []byte? thanks > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
