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From: tim@amdcad.AMD.COM (Tim Olson)
Newsgroups: comp.unix.wizards
Subject: Re: have I found a bug in K&R?
Message-ID: <18668@amdcad.AMD.COM>
Date: Tue, 13-Oct-87 11:46:52 EDT
Article-I.D.: amdcad.18668
Posted: Tue Oct 13 11:46:52 1987
Date-Received: Thu, 15-Oct-87 00:37:07 EDT
References: <517@hubcap.UUCP> <321@laticorp.UUCP> <7608@steinmetz.steinmetz.UUCP>
Reply-To: tim@amdcad.UUCP (Tim Olson)
Organization: Advanced Micro Devices
Lines: 26
Keywords: argv definition
Summary: You're both right

In article <7608@steinmetz.steinmetz.UUCP> dawn!stpeters@steinmetz.UUCP (Dick St.Peters) writes:
| In article <321@laticorp.UUCP> sarah@laticorp.UUCP (Sarah Groves Hobart) writes:
| >Remember that the following declarations are equivalent:
| >
| >char s[];
| >
| >char *s;
| 
| Actually, they're not.  The difference is like that between a constant
| and a variable: you can change the value of s (the address it points
| to) if you declare it as a pointer [variable], but you can't if you
| declare it as an array [constant].  Consider what "&s" means in the
| two cases.

Actually, you are both right.  There are two places where a declaration
of an array with no size (and no initializer) are legal: 1) as a formal
parameter, and 2) as an external array declaration, where the array is
defined elsewhere.

As a formal parameter, char s[] and char *s are equivalent -- the
compiler coerces the former into the later.  In that case you *can*
change s.  As an external array declartion, the two are not equivalent.

	-- Tim Olson
	Advanced Micro Devices
	(tim@amdcad.amd.com)