Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!lll-winken!unixhub!shelby!neon!rfischer
From: rfischer@Neon.Stanford.EDU (Raymond C. Fischer)
Newsgroups: comp.sys.mac.programmer
Subject: Re: 'am I dead yet?', or, debugging
Message-ID: <1990Oct24.200647.22234@Neon.Stanford.EDU>
Date: 24 Oct 90 20:06:47 GMT
References: <15998@csli.Stanford.EDU>
Organization: Computer Science Department, Stanford University
Lines: 23

In article <15998@csli.Stanford.EDU> ramaley@csli.Stanford.EDU (Alan Ramaley) writes:
>The problem?  Everytime I run it, it crashes at some point.  And it
>crashes completely, that is, the think C debugger breaks, I don't even
>get a 'bus error' or anything like that.
>
>(2)	Figure out where you are in the program using the debugger?

Think C's debugger, while very good, probably won't do it for you.
What I do is turn off the C debugger, let the program die, then use 
Macsbug to find out what's doing.  In particular, use the commands ...
  HC (heap check) to see if your trashing the heap
  SC6 (stack crawl) to trace through the activation records, and
  SC7 (stack crawl) in case SC6 doesn't work.
You should have compiled your program with the 'Macsbug Symbols' option
checked so you can actual procedure names displayed.

Taking a wild guess at your problem, I'd say that you're assuming some
handle is in a place it no longer occupies.  Keep in mind that the object
of a handle can move.  If you use a pointer to an object over many system
calls, the object may move and you will overwrite the wrong thing.

Ray Fischer
rfischer@cs.stanford.edu