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From: jhritz@cfpas.UUCP (John Hritz)
Newsgroups: comp.lang.c
Subject: Re: C arrays of strings
Message-ID: <231@cfpas.UUCP>
Date: Wed, 18-Nov-87 14:54:05 EST
Article-I.D.: cfpas.231
Posted: Wed Nov 18 14:54:05 1987
Date-Received: Sat, 21-Nov-87 12:16:45 EST
References: <3157@rosevax.Rosemount.COM>
Reply-To: jhritz@cfpas.UUCP (John Hritz)
Organization: Chrysler FPAS, Southfield, MI
Lines: 66
Keywords: C

In article <3157@rosevax.Rosemount.COM> richw@rosevax.UUCP writes:
>Could someone explain the following declaration in english and
>give an example of how to use it? I believe I can use this declaration
>but cannot explain how is works. What I'm after is simply an array of
>character strings.
>
>  char *str[12];

Although it is not fool proof, a useful method for converting C declarations
to English is to use the outside/inside rule, using the type and variable
names as your boundaries. Using your example, char *str[12] would be
translated to "str is an array of 12 pointers to characters". Using one
of favorite examples in K and R, this construct could be used to store
a list of months.  Each month is variable length, you have only a pointer to
where the characters are stored.  Like so,

static char *str[] =
	{
	"January",
	"February",
	"March",
	"April",
	"May",
	"June",
	"July",
	"August",
	"September",
	"October",
	"November",
	"December"
	};
Note that in the absence of a declared size of the array, the compiler will
calculate the number of elements, in this case 12.

This contrasts with declaring the length of each of the elements which looks
similar. Ex.
static char str[][80] =
	{
	"January",
	"February",
	"March",
	"April",
	"May",
	"June",
	"July",
	"August",
	"September",
	"October",
	"November",
	"December"
	};
This will calculate the number of initializers but then allocate 80 characters
for each line.  Its not useful in this example, but its often done to 
initialize strings with default values and  allow the user of the
application to alter their contents with entries up to 80 characters long.


So, to create an array of strings, the declaration would be something like
char str[10][80] or in english "an array of 10 strings each 80 characters in
length.

For more information on creating and reading C type declarations refer to
The C Programming Language, Kerninghan and Ritchie, pp 194-195.
-- 
UUCP: ihnp4!mibte!cfpas!jhritz (John Hritz)  "Do photons have mass?...
VOICE: 313-351-3485                               Are any of them Catholic?"