NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/comp/lang/c/19147

Text File | 1993-01-03 | 2.8 KB | 87 lines

Newsgroups: comp.lang.c
Path: sparky!uunet!zaphod.mps.ohio-state.edu!moe.ksu.ksu.edu!usenet-feed.cc.umr.edu!mcastle
From: [e-mail] (Michael R Castle)
Subject: Re: [FAQ] size of executables ?
References: <[e-mail]>
Date: Sun, 3 Jan 1993 07:14:30 GMT
Nntp-Posting-Host: next9.cs.umr.edu
Organization: University of Missouri - Rolla, Rolla, MO
Sender: [e-mail] (UMR Usenet News Post)
Message-ID: <[e-mail]>
Lines: 74

In article <[e-mail]> <[e-mail]> writes:
>Hi, my question may be a faq, but I am asking it nevertheless.
>
>How does one compile a c program so that the size of the
>executable is as small as possible. I noticed that even a
>trivial program like Hello.c  produces a huge executable,
>perhaps due to the include files stdio.h etc. Of course,
>I can not do any i/o without stdio.h . On the other hand,
>I am not using all the stuff that's there in stdio.h, and
>feel that the size of the executable should be proportional
>to what I am using. Any suggestions ?

printf() is huge.  Anyprogram that uses printf() has the potential for creating
a large exectuable.

Try this:

#include <stdio.h>

int main(void) {
  printf("line 1\n");
}


then:

#include <stdio.h>

int main(void) {
  printf("line 1\n");
  printf("line 2\n");
}


Compare the size of the executables.  Probably pretty close.  It's not so
much how many function calls, but what functions you are calling.

I imagine puts() is much smaller than printf().

Try

#include <stdio.h>

int main(void) {
  puts("line 1\n");
}

And see if that is any smaller than using printf().

Of course, then you loose functionallity.

You could try to simulate printf() functionallity using sscanf() and puts()
but I imagine sscanf is nearly as large as printf() so you wouldn't get
anyway. (Maybe both link in the same code?)

Anyway, smart linkers (like Borlands) does try to link in only function that
are actually called, so not all the functions listed in stdio.h are linked in.

Matter of fact, man compiler (at least on unix systems) are putting more and
more of all the prototypes into one (large) .h file.  I imagine the original
reason for not including all the of the standard system libs into one large
file in the first place was because of slower systems.  Filtering out all the
stuff in the .h file you don't actually use was too slow.  Now days, compilers
are usually fast enough that that extra overhead is not noticable (of course,
this limits defining your own functions that have the same name, but oh
well).

enough ramblings,
mrc
--
Mike Castle .-=NEXUS=-.  Life is like a clock:  You can work constantly
  [e-mail]     and be right all the time, or not work at all
[e-mail]   and be right at least twice a day.  -- mrc
    We are all of us living in the shadow of Manhattan.  -- Watchmen