Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!wasatch!cmos.utah.edu!jacobs
From: jacobs%cmos.utah.edu@wasatch.utah.edu (Steven R. Jacobs)
Newsgroups: comp.sys.ibm.pc
Subject: Re: How Turbo C Handles Null Pointer Assignments
Message-ID: <1778@wasatch.utah.edu>
Date: 10 May 89 18:17:04 GMT
References: <4178@sybase.sybase.com>
Sender: news@wasatch.utah.edu
Organization: University of Utah CS Dept
Lines: 12

In article <4178@sybase.sybase.com> forrest@sybase.com writes:
>After looking at the c0m.asm source code supplied with Turbo C I
>figured out what was going happening. Turbo C stores a check sum
>of the memory area starting with address 0 and continuing through
>where the message is stored that you see when you run Turbo C.

This "checksum" is actually the Turbo C copyright string.  If it
gets tromped on, the "Null Pointer Assignment" message is given.
You can verify this by looking at location 0 with the debugger,
assuming you look there before your program tromps on the data.

Steve Jacobs  ({ihnp4,decvax}!utah-cs!jacobs, jacobs@cs.utah.edu)