Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucsd!ogccse!orstcs!prism!johng
From: johng@prism.cs.orst.edu (John A. Gregor)
Newsgroups: comp.lang.c
Subject: Re: Test of possible ACSGATE on net
Message-ID: <13130@orstcs.CS.ORST.EDU>
Date: 16 Oct 89 03:09:44 GMT
References: <16103@nswitgould.cs.uts.oz>
Sender: usenet@orstcs.CS.ORST.EDU
Reply-To: johng@prism.CS.ORST.EDU (John A. Gregor)
Organization: Oregon State Univ. -- Computer Science
Lines: 26

In article <16103@nswitgould.cs.uts.oz> garth_kidd%680.808@fidogate.fido.oz (Garth Kidd) writes:
>Can anyone think of a tighter way of coding a filter to strip spaces
>from the input stream than this?
>
>main()
>{
>  char ch;
>
>  for(;read(0,&ch,1)==1;write(1,&ch,(ch==' ')?0:1))
>    ;
>}

Ick!  Yuk!  First, there are no awards for 'tight' source (small does not
mean efficient).  The killer is the 1 character reads and writes.  There
is this little problem with system calls, it's known as overhead.  For each
system call, your machine will have to do 2 context switches which are
pretty expensive.

Although it is more programmer work, what you should do is create two
large buffers (one for reading and one for writing).  Or you can use
fread and fwrite, or getc and putc, which are also buffered.

Lastly, do you have something against whitespace???

John Gregor
johng@cs.orst.edu