From:	Konstanty <M DOT Bialkowski AT mailbox DOT uq DOT edu DOT au>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Questions about DJGPP + Allegro
Date:	Wed, 27 Jan 1999 10:17:38 +1000
Organization:	University of Queensland
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Message-ID:	<36AE5B21.9BEE6CC0@mailbox.uq.edu.au>
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

I have a game that I am making that keeps crashing.

I know that something is corrupting memory but I'm not sure what.

The program usually crashes when it tries to draw a BITMAP whose pointer
has been stuffed up.

How do I check whether a BITMAP * is really a bitmap.

The BITMAPs are inside a array of Buttons (which is initilised with
'new'). The Buttons cantain information about thier location (4 ints)
and the bitmaps. The locations of the first 5 seem to be filled with
information from the bitmap (The bitmap is a 16-bit bitmap).

0. (537996,189548)-(189548,1331464)
1. (1333704,1333864)-(1334024,1334184)
2. (1337384,1337544)-(1337704,1337864)
3. (1341064,1341224)-(1341384,1341544)
4. (7,175)-(85,255)
5. (90,175)-(170,255)
6. (5,260)-(85,340)
7. (90,260)-(170,340)

The array of locations should be:
0. (5,5)-(85,85)
1. (90,5)-(170,85)
2. (5,90)-(85,170)
3. (90,90)-(170,170)
4. (5,175)-(85,255)
5. (90,175)-(170,255)
6. (5,260)-(85,340)
7. (90,260)-(170,340)

Also does anyone have any suggestions on how I can debug this program?

I currently am using a log file using fopen, fprintf and fclose. When
the program crashes it only saves up to the last fclose. How can you
make it close the file before it exits. I have tried an atexit routine -
but it doesnt work.

I can supply some code if that is needed as well.

Konstanty

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