From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Polymorphism in C
Date:	25 Jun 2002 07:18:37 GMT
Organization:	Aachen University of Technology (RWTH)
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Pedro Izecksohn <izecksohn AT yahoo DOT com> wrote:
>    Hi,

>    In C++ polymorphism is possible, declaring more than
> once the same function with different parameters, like the
> example bellow:

> void something (int);  
> void something (int *);

>    Is it possible in C, without using the va_* functions?

Hardly.

> How?

By doing it the same way C++ does it, too --- mostly behind the
scenes.  You have to "decorate" or "mangle" the names of the function
to include the types of the arguments it takes.  GCC-2.8.1, e.g., will
silently rename the above functions to

	something__Fi
and	something__FPi

respectively, meaning "function called 'something', taking an int" and
"function called 'something' taking a pointer to an int".

Obviously, that's no fun at all to write by hand.  Looked from this
angle C++ is mainly a powerful preprocessor for C.  Actually that's
exactly what one of the first few C++ compilers in existence was: a
preprocessor that created (almost) normal C source to be passed on to
the (only slightly extended) C compiler.
-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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