From: mapson AT mapson DOT com (mapson)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: allegro program dies under dos
Date: Sun, 22 Jun 1997 00:19:58 GMT
Organization: Yale University
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References: <33ac0166 DOT 1100296 AT news DOT demon DOT co DOT uk> <Kk7BdBA3aBrzEw+g AT talula DOT demon DOT co DOT uk>
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On Sat, 21 Jun 1997 19:00:23 +0100, Shawn Hargreaves
<Shawn AT talula DOT demon DOT co DOT uk> wrote:

>>my allegro program works fine in 95 but not at all from dos 
>>and i have cwsdpmi in the program dir.
>>anyone know whats up ?
>
>At a guess, you are dereferencing a NULL pointer somewhere in your code.
>Win95 lets you get away with this, while cwsdpmi does a proper job of
>trapping the error. Compile your program with the -g option and run
>'symify progname.exe' after it crashes, to find out exactly where it is
>dying...
>
>btw. a more detailed description than "works not at all" would be kind
>of useful :-)

I'm pretty sure you are right. 

I had a similar problem once- I had compiled a program with some code
trying to open a PCX file that didn't exist. I no longer used the PCX
in the program, but missed excising the code that tried to open it.
Win95 ran it fin, and Win3.x ran it fine, but DOS wouldn't go with it.


Took a while to figure out what was up. But at least it got me to
clean up my code.