From:	geirt AT powertech DOT no (Geir Thomassen)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Error when optimising ??
Date:	Thu, 19 Jun 1997 13:57:33 GMT
Organization:	Jotron Electronics
Lines:	61
Message-ID:	<5obdsi$5fq$1@troll.powertech.no>
NNTP-Posting-Host:	gw1-1.sandefjord.no.powertech.net
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I have a small program that behaves differently
when optimised. Why ?? Am I using sprintf wrong ??
Compiler bug ??

I am using plain DJGPP v2.01, no PGCC. I beleve the program
worked under DJGPP 2.00. (At least I didn't notice any
problems with my code before I upgraded..)

Here is the source:

------------------
#include <stdio.h>

int main (int argc, char *argv[])
{
  int n;
  int r;
  unsigned long o;

  if (sscanf ("1020304050", "%02X%04lX%02X", &n, &o, &r) != 3)
    {
      printf("fscanf failed\n");
      return -1;
    }

  printf("n=%X (should be 10)\n",n);

  return 0;
}
----------------------------

This is what happends (in a win95 shell):

C:\Usr\tst>gcc -Wall tst.c -o tst.exe

C:\Usr\tst>tst
n=10 (should be 10)

C:\Usr\tst>gcc -Wall -O tst.c -o tst.exe

C:\Usr\tst>tst
n=0 (should be 10)

C:\Usr\tst>

----------------------------
Any idea ??
  Geir



| Geir Thomassen,                 | geirt AT powertech DOT no      |
| R&D Engineer, electronics (MSc) | LA7HFA, qrv 2.45GHz :-) |
|                                 |                         |
| Jotron Electronics a.s.         | Phone +47 33139700      |
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