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From: rmartin@clear.com (Bob Martin)
Newsgroups: comp.lang.c,alt.religion.computers
Subject: Re: ANSI C prototypes
Message-ID: <1990Nov6.002848.3634@clear.com>
Date: 6 Nov 90 00:28:48 GMT
References: <1005@christopher-robin.cs.bham.ac.uk> <1906@necisa.ho.necisa.oz> <RJC.90Nov1145211@brodie.uk.ac.ed.cstr>
Organization: Clear Communications, Inc.
Lines: 48

In article <1906@necisa.ho.necisa.oz> 
boyd@necisa.ho.necisa.oz (Boyd Roberts) writes:
>
>    Right on!  The function prototypes are just stupid.  I shouldn't have to go:
>
>	extern gore	*good(const char *vomit);
>
>    to get the functionality of type checking of function arguments.
>    The compiler and loader should do it.  
>

The C++ compiler does this.  If you declare a function one way
and use it in another, say with different type arguments, then the
program won't link.  C++ does this by mangling the return type and
argument types into the function name.  Thus when you declare
a function:  int x(int y)  the compiler generates a new name
for the function which is what the loader sees.  This name would
specify that the function's name was x, that it returned an int and
that it had a single int parameter.

So if you screw up your declarations, or attempt to use implicit
declarations (bad style), you cannot get a runtime error becuase
of a type mismatch.  The linker will catch the problem.

--

By the way, this technique of mangling the function names means that

	int x(int y);
		and
	double x(double y);

are completely different functions.  You can declare both of them,
define them separately and call the proper function by making sure
that the types are correct.

+----------------------+---------------------------------------------+
| Robert C. Martin     | The authors opinions are his own and do not |
| rmartin@clear.com    | represent the opinions of his employer.     |
| uunet!clrcom!rmartin |                                             |
+----------------------+---------------------------------------------+


-- 

+----------------------+---------------------------------------------+
| Robert C. Martin     | The authors opinions are his own and do not |
| rmartin@clear.com    | represent the opinions of his employer.     |