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From: mouse@thunder.mcrcim.mcgill.edu (der Mouse)
Newsgroups: comp.lang.c
Subject: Re: More problems with passing functions as arguments.
Message-ID: <1991Mar23.104656.13780@thunder.mcrcim.mcgill.edu>
Date: 23 Mar 91 10:46:56 GMT
Article-I.D.: thunder.1991Mar23.104656.13780
References: <27546@uflorida.cis.ufl.EDU>
Organization: McGill Research Centre for Intelligent Machines
Lines: 38

In article <27546@uflorida.cis.ufl.EDU>, pm0@reef.cis.ufl.edu (Patrick Martin) writes:
[code compressed to save lines -dM]
> void Function(i)
> int i;
> { printf("\nThe Number Is: %d\n",i); }

> void Pass_Me_A_Function(F)
> void (*F) (int);
> { F(1); }

> main()
> { Pass_Me_A_Function(Function); }

> This code works fine when compiled with gcc or my compiler at home.
> When compiled with some of the older implementations of C it fails.

> It fails on the declaration of F in Pass_Me_A_Function of
> void (*F) (int);

The "older" implementation probably does not understand prototypes.
Remove the argument type declaration; try just void (*F)(); and see if
it works an;y better.

With some, you may find you also have to write the call as (*F)(1);.
There are no compilers I am sure this is necessary for, but I have seen
only a tiny fraction of all compilers in existence :-)

In passing, why do you prototype the argument to Pass_Me_A_Function but
not anything else?  I would argue on stylistic grounds that Function
should be prototyped to match the argument to Pass_Me_A_Function,
though I think the given prototype is compatible with the given
old-style declaration.

					der Mouse

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