Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!amdahl!nw
From: nw@amdahl.uts.amdahl.com (Neal Weidenhofer)
Newsgroups: comp.lang.c
Subject: Re: Teaching const
Message-ID: <27071@amdahl.uts.amdahl.com>
Date: 8 Apr 88 07:30:15 GMT
References: <7712@apple.Apple.Com> <3034@haddock.ISC.COM> <613@mcrware.UUCP> <7788@alice.UUCP>
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 50
Summary: Close but no cigar

In article <7788@alice.UUCP>, bs@alice.UUCP writes:
> Try reading C declarations backwards (from right to left) they often
> make sense that way.

The way to read them is from the "inside out".  Start with the identifier
being declared.  The closest type/"*"/"[...]"/"(...)" describes it.
The next closest describes that and so on.  Just remember that, in the
absence of parentheses, things on the right ("[...]" and "(...)") are "closer"
than things on the left ("*", etc.).  The only exception is storage class
which ALWAYS applies directly to the identifier being declared.

For example:
	int * const a;
decodes as:
	a is a constant,
	a is a constant pointer,
	a is a constant pointer to an int.
		(i.e., a cannot be modified but *a can.)
while:
	const int * a;
means:
	a is a pointer,
	a is a pointer to an int,
	a is a pointer to a constant int (or int constant.)
		(i.e., *a cannot be modified but a can.)
and a toughie:
	int (*a[])();
means:
	a is an array (remember right is "closer" than left)
	a is an array of pointers,
	a is an array of pointers to functions,
	a is an array of pointers to functions that return int.

Please, please, please, if you're teaching C, teach them to decode 
declarations this way.  They'll bless you for it.

>		       The ones that don't you might consider simplifying
> using typedef.

This is ALWAYS a good idea if declarations become unmanageable.

The opinions expressed above are mine (but I'm willing to share.)

			Regards,
				Neal Weidenhofer
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