From:	adwyer AT galaxy DOT csc DOT calpoly DOT edu (Aaron Dwyer)
Newsgroups:	comp.os.msdos.djgpp
Subject:	GDB debugging
Date:	Sun, 24 Nov 1996 11:07:35 GMT
Organization:	Cal Poly, San Luis Obispo
Lines:	21
Message-ID:	<579aaf$l6k@isnews.csc.calpoly.edu>
NNTP-Posting-Host:	p102-13-w.palomar.reshall.calpoly.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

	I'm currently finishing up an implementation of quicksort in DJGPP to
sort polygons far to near, classic painter's algo situation...BUT...my
quicksort doesn't seem to agree with the type of data structures I'm
using or something.  Anyways, GDB is telling me that it crashes
somewhere deep into the recursion on the line which calls quicksort
recursively to process the left-hand partition of the array being
sorted. The line reads:  quicksort(lo, thi);   

	What kinds of clues regarding my bug can I get from knowing the
program crashes on a function calling line?  It can't be stack
overflow because I'm only sorting 100 values in this test case...0-99
values works perfectly, but 100+ values will cause a crash :I  

	I guess this question concerns what I can learn from GDB more than
anything, because my quicksort will work for sorting a plain old
integer array, in fact I can sort a 10000 value array just fine, but
when I try to sort a list of polygons it will only do 0 - 99 before it
seg faults on that line as mentioned above.  Comments, questions,
truly anything you have to tell me will help =)  
					Thanks, Aaron Dwyer

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