From: Christoph Kukulies <kuku AT gilberto DOT physik DOT rwth-aachen DOT de>
Message-Id: <199701081113.MAA01144@gilberto.physik.rwth-aachen.de>
Subject: Re: free() question
In-Reply-To: <32D35994.43BD@post.comstar.ru> from Dim Zegebart at "Jan 8, 97 11:23:48 am"
To: zager AT post DOT comstar DOT ru
Date: Wed, 8 Jan 1997 12:13:09 +0100 (MET)
Cc: djgpp AT delorie DOT com
Reply-To: Christoph Kukulies <kuku AT gilberto DOT physik DOT rwth-aachen DOT de>
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> Hi,
> 
> Just a small question about free() function
> 
> Let's :
> 
> char *ptr1,*ptr2;
> 
> ptr1=(char*)malloc(sizeof(char)*1024);
> if (ptr1!=NULL) ptr2=ptr1;
> ....
> 
> //so my question. May i use 
> free(ptr2);

Yes, you may use ptr2 as well. It's the address that corresponds to
the malloc that's freed, not the pointer.
But beware, in the example given you should only free(ptr1)
or free(ptr2) if ptr1 or ptr2 have been initialized
to some senseful value.

In the above code portion ptr2 doesn't get initialized and if
the malloc returned a 0 for some reason you would invoke
free() later with a wild pointer.

> //or i have to use
> free(ptr1)
> 
> -- 
> Regards,
> Dim Zegebart,
> Moscow Russia.
> 

--Chris Christoph P. U. Kukulies kuku AT gil DOT physik DOT rwth-aachen DOT de