How to program/test for portability?

[Edward J Driscoll]

I'm not sure what compiler you're going to use, but some of them
have the ability to turn off all non-ANSI extensions with the
flick of an option somewhere.  You can do this in TurboC (a DOS
compiler), and I'd imagine many compilers have this sort of option.

The TurboC manuals also have a PORTABILITY note in the description
of each of the library functions, with things like "compatible with
ANSI", "defined in K&R", or "unique to DOS".  A friend of mine
was recently telling me about a reference book which cross-referenced
a list of standard library functions with a list of operating systems
which typically support them.  I can't remember what the title is
off hand, perhaps someone else....?

-- 
Ed Driscoll
The University of Michigan
ejd at caen.engin.umich.edu