Q67084: Make Your Function Return Zero When Redefining _nullcheck()

Article: Q67084
Product(s): See article
Version(s): 6.00 6.00a | 6.00 6.00a
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | docerr S_QUICKC | mspl13_c
Last Modified: 18-DEC-1990

By default, Microsoft C checks the NULL segment before the final
termination of a program in order to determine if a null pointer
assignment has occurred. This check can be suppressed by defining your
own function called _nullcheck(), which is the name of the library
routine that is normally linked in to do the checking.

The online help for C versions 6.00 and 6.00a and QuickC versions 2.50
and 2.51 describes how to replace this function, but there is an error
in the help files. The help states that you just need to declare your
own routine "named _nullcheck that does nothing". This is not
completely true. You actually need to make your function return a
value of zero; otherwise, the program exit code will be set to 255.

The following is a valid way to define the _nullcheck() function in
your program:

    int _cdecl _nullcheck( void)
    {
        return (0);
    }

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