Xref: utzoo comp.sys.m6809:711 comp.lang.c:8062
Newsgroups: comp.sys.m6809,comp.lang.c
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Don't use Scanf()
Message-ID: <1988Mar13.005841.12770@utzoo.uucp>
Keywords: C stdio library
Organization: U of Toronto Zoology
References: <2401@ihwpt.ATT.COM> <320@c10sd1.StPaul.NCR.COM> <1185@ucsfcca.ucsf.edu>, <9241@sunybcs.UUCP>
Date: Sun, 13 Mar 88 00:58:41 GMT

> 	For example, if you want to print a string fast, you would write
> a routine that uses only putc...

!!NO!!  If you want to print a string fast, you use fputs and insist that
your supplier implements it properly.  Putc has to do things like buffer-
overflow checking on every character; a fast implementation of fputs can
inspect the buffer *once*, note that there is room for N more characters,
copy N characters at high speed, and then update counts and so forth *once*.
This is a major efficiency win over putc if you are doing it a lot.

Unfortunately, not all implementors make the effort to make stdio fast.
In general, System V stdios are fast and 4BSD ones are not.  (There are
exceptions to this, both ways, and I believe the 4BSD one is going to be
improved.)
-- 
Those who do not understand Unix are |  Henry Spencer @ U of Toronto Zoology
condemned to reinvent it, poorly.    | {allegra,ihnp4,decvax,utai}!utzoo!henry