Path: utzoo!utgpu!jarvis.csri.toronto.edu!me!radio.astro!helios!dooley
From: dooley@helios.toronto.edu (Kevin Dooley)
Newsgroups: comp.lang.c
Subject: Solution of array of pointers to functions problem
Message-ID: <823@helios.toronto.edu>
Date: 13 Jun 89 18:33:31 GMT
Reply-To: dooley@helios.physics.utoronto.ca (Kevin Dooley)
Distribution: na
Organization: University of Toronto Physics/Astronomy/CITA Computing Consortium
Lines: 43

In a very recent posting I asked why it was illegal to construct
an array of pointers to functions.  The answer is, of course, that
it is completely legal, but with a twist.  The answer was graciously
suplied by Steve Lamont (thanks again).  Here is the expurgated version
of what he said:

>  ...Assuming that you want to do something like
>
>	double	foo();
>	double	bar();
>	double	baz();
>	double	woof();
>	double	arf();
>
>	typedef double	(*function)();
>
>	function	functionList[] = { foo, bar, baz, woof, arf };
>
>you can then invoke your favorite function in the following manner:
>
>	someReturnValue = (*functionList[index])( your favorite args );

Steve points out that the typedef is critical, ie

	double	(*functionList[])() = { ... };

*DOES**NOT**WORK*.  This is the peculiarity that I was missing.  Now
everything works beautifully.  So the big question at this point is
why is the typedef necessary?  I thought that typedef was *NEVER* 
required.  Anybody know the answer?

PS.  I'd like to thank all of the people who supplied correct responses.
I mention Steve's only because it was so concise, correct and ... well,
first.  I do not thank any of the people who assumed that I was a complete
idiot (no names, you know who you are).  As you see, there was something
nontrivial involved and the subject is not covered in either K&R.

		Kevin Dooley

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