Null Pointer Assignment

[Dan Schikore]

What exactly does the run-time error "Null Pointer Assignment" mean?  I get
this error after a series of recursive calls to a function, but the error does
not come up until the end of the program.  In fact, I put in the line

printf("done\n");
exit(0);

at the end of my main, and when executed, it says

done
Null Pointer Assignment

Does this make sense?  Thanks for any suggestions.

-Dan Schikore
schikore at mentor.cc.purdue.edu