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From: kocks@jessica.stanford.edu (Peter Kocks)
Newsgroups: comp.sys.mac.programmer
Subject: NULL pointer problem in THINK_C?
Keywords: THINK_C,bug
Message-ID: <1990Aug14.164700.146@portia.Stanford.EDU>
Date: 14 Aug 90 16:47:00 GMT
Sender: news@portia.Stanford.EDU (USENET News System)
Organization: Academic Information Resources
Lines: 32

I ran into a strange problem the other day using THINK_C.

Consider the following two codes....

a)
while(mypointer != NULL){ .... }

b)
while(((int)(mypointer)) != 0){ ... }


I found that a) does not work.  I.e. when mypointer == NULL (as shown
by the debugger), the "while" statement continues to execute.  On the
other hand (b)  (which should be functionaly equilavent) does work.

I am using think_c 4.0, with the scanf patch, but no others.

Please respond also be e-mail.

-- Peter Kocks
   kocks@jessica.stanford.edu

P.S

Debugger Notes:

Variable        :   Value
-------------------------
mypointer       : 0x000...
NULL            : 0x000...
mypointer != NULL : 1
mypointer == NULL : 0