My program ran fine under cygwin 1.5 as well as many versions of 
linux including
mandriva 2009, mandriva 2009.1 and mandriva 2010.0

When compiled with
gcc cal.c -o cal
and run with
cal 2009
I get a segmentation fault.
When I uncomment line 62, the program runs successfully.

I have had other problems with recent versions of cygwin 1.7 which 
makes me suspect
some kind of error outside my programs.

thanks,
jeff