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From: jv@mhres.mh.nl (Johan Vromans)
Newsgroups: comp.lang.c
Subject: Re: Allocation for pointers
Message-ID: <1272@mhres.mh.nl>
Date: Fri, 4-Sep-87 17:05:13 EDT
Article-I.D.: mhres.1272
Posted: Fri Sep  4 17:05:13 1987
Date-Received: Sun, 6-Sep-87 02:08:26 EDT
References: <1357@faline.bellcore.com>
Reply-To: jv@mhres.mh.nl (Johan Vromans)
Organization: Multihouse N.V., The Netherlands
Lines: 34

In article <1357@faline.bellcore.com> gtchen@faline.UUCP (George T. Chen) writes:
>I have a question about the following program:
>
>main() { char *a; a = "text"; recurs(a);}
>
>void recurs(a) 
>char *a; 
>{	strcat(a,"more text");
>	if (some conditional test) recurs(a);
>}
>
>As I understand it, I'm passing the address of the variable a into
>the routine recurs.  At no point do I specify how large of a buffer
>a will eventually point to.  Is there a limit and is it compiler
>dependent?

Your pointer is pointing in your program space. The "strcat" is therefore
overwriting your program. Depending on how the compiler/linker have
arranged your program and data, disaster will result pretty soon.
The precise result is implementation dependent. Imagine the original text
being placed on the stack ...

--
Johan Vromans                              | jv@mh.nl via European backbone
Multihouse N.V., Gouda, the Netherlands    | uucp: ..{?????!}mcvax!mh.nl!jv
"It is better to light a candle than to curse the darkness"




-- 
Johan Vromans                              | jv@mh.nl via European backbone
Multihouse N.V., Gouda, the Netherlands    | uucp: ..{?????!}mcvax!mh.nl!jv
"It is better to light a candle than to curse the darkness"