Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rochester!crowl
From: crowl@rochester.arpa (Lawrence Crowl)
Newsgroups: comp.lang.c
Subject: Re: help with declaration
Message-ID: <364@sol.ARPA>
Date: Thu, 18-Jun-87 08:59:11 EDT
Article-I.D.: sol.364
Posted: Thu Jun 18 08:59:11 1987
Date-Received: Sun, 21-Jun-87 11:52:02 EDT
References: <8286@ut-sally.UUCP> <7001@alice.UUCP>
Reply-To: crowl@rochester.UUCP (Lawrence Crowl)
Organization: U of Rochester, CS Dept, Rochester, NY
Lines: 42
Keywords: function pointer

In article <7001@alice.UUCP> ark@alice.UUCP writes:
>The problem: how to declare a function that returns a function pointer:
>
>..., so we should say
>
>	extern int (*getfunc())();
>
>All clear?

This is not clear.  Let me propose a method for clearly coding complex
declarations.  I make use of the typedef facility.  So, for the example
above I will write:

     typedef  int                func_int() ;
     typedef  func_int           *ptr_func_int ;
     typedef  ptr_func_int       func_ptr_func_int() ;

     extern   func_ptr_func_int  getfunc ;

So what does this method buy me?  Well, it gives me a way to declare
other complex types without consulting K&R and a couple of C wizards
just to make sure the syntax is correct.  For instance, how about a
pointer to a function returning a pointer to an integer?

     typedef  int               *ptr_int ;
     typedef  ptr_int           func_ptr_int() ;
     typedef  func_ptr_int      *ptr_func_ptr_int ;

     extern   ptr_func_ptr_int  variable ;

What have I lost?  Well I have to type more.  However, the typedefs
need only be done once, so the true comparison is between:

     extern   int  (*getfunc())() ;
and
     extern   func_ptr_func_int  getfunc ;

I prefer the latter.
-- 
  Lawrence Crowl		716-275-5766	University of Rochester
			crowl@rochester.arpa	Computer Science Department
 ...!{allegra,decvax,seismo}!rochester!crowl	Rochester, New York,  14627