ID Number: Q76945
6.00
MS-DOS
buglist6.00 fixlist6.00a
Summary:
PROBLEM ID: C9110001
SYMPTOMS
The sample program BELL.C, which is shipped with the Microsoft
Macro Assembler (MASM) version 6.0, generates the following error
when compiled and run:
run-time error R6001
- null pointer assignment
CAUSE
The run-time error R6001 occurs because the error-checking routine
_nullcheck() is being invoked after the program has terminated to
determine whether the contents of the NULL segment have been
changed. Because this is a mixed C and assembly language program,
the _nullcheck() routine is expecting to see the Microsoft C
run-time library message in the NULL segment.
However, because of the segment ordering that is done in the
assembly code, this is not what is actually in the NULL segment.
Although the code in the NULL segment is correct, it is not in the
order that _nullcheck() is expecting.
RESOLUTION
As stated in the online help, the null pointer check can be
suppressed by defining your own routine named _nullcheck() that
does nothing. To prevent the above error, place the following
_nullcheck() definition in the file BELL.C.
void _nullcheck (void)
{
}
The /NOE link option must also be used to avoid multiple symbol
definitions. The call to _nullcheck() will be satisfied by your
definition of _nullcheck(), and the library version will not be
loaded.
STATUS
Microsoft has confirmed this to be a problem in MASM version 6.0.
This problem was corrected in MASM version 6.0a.
Additional reference words: BELL.MAK