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From: dkeisen@Gang-of-Four.Stanford.EDU (Dave Eisen)
Newsgroups: comp.lang.c
Subject: Re: Declaration Question
Message-ID: <10847@polya.Stanford.EDU>
Date: 25 Jul 89 03:11:25 GMT
References: <394@dftsrv.gsfc.nasa.gov> <1242@atanasoff.cs.iastate.edu>
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Reply-To: dkeisen@Gang-of-Four.Stanford.EDU (Dave Eisen)
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Organization: Mathematics Department, Stanford University
Lines: 37
In-reply-to: hascall@atanasoff.cs.iastate.edu (John Hascall)

In article <1242@atanasoff.cs.iastate.edu>, hascall@atanasoff (John Hascall) writes:
>In article <394> setzer@nssdcs (William Setzer (IDM)) writes:
>>Will this declaration:
> 
>>char *foo[K][N];
> 
>>  foo
>>   |
>>   v
>>+-------+      +---...---+
>>| ptr1 ------> | N chars |
>>+-------+      +---...---+
>>| ptr2 ------> | N chars |
>>+-------+      +---...---+
>>|   :   |      |    :    |
>
>   "char *foo[K][N]" is "array K of array N of pointer to char" which doesn't
>   match your picture, how about "char (*foo[K])[N]" which is "array K of
>   pointer to array N of char" which seems to match your picture--and you
>   will need to malloc the K sets of "N chars" yourself:


As I read his diagram, foo is a *pointer* to an array K of pointers to array
N of char. So foo is declared:


char  (*(*foo)[K])[N]

and the declaration of foo will only allocate the initial pointer. To
allocate everything you have here, you have to malloc space for an array of
pointers and then do the same for the characters each of these pointers
points to.


Dave Eisen 	 	                                (415)723-2963 "work"
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