Re: Malloc()
Re: Malloc()
- Subject: Re: Malloc()
- From: Jonathan Wight <email@hidden>
- Date: Tue, 02 Apr 2002 12:12:19 -0600
On 04/02/2002 11:31, "Vince DeMarco" <email@hidden> wrote:
>
On Monday, April 1, 2002, at 10:49 PM, Jason Moore wrote:
>
>
> Hello all.. Sorry to keep bothering everyone with C questions, but this
>
> one has me totally stumped..
>
>
>
> I need to pass some data (in the form of a char* buffer) into a Unix
>
> library function. I'm getting my data from an NSData object using
>
> GetBytes:range:. My problem is that my buffers are not working.
>
>
>
> i have:
>
>
>
> char *buffer;
>
> buffer = malloc(bufferSize);
>
> NSLog(@"buffer size is: %i", sizeof(buffer));
>
>
>
> here is where the problem is. the log output is 'buffer size is: 4', even
>
> when i change the malloc
>
> statement to read buffer = malloc(129) (129 is the size of the buffer i
>
> need in my test case).
>
>
>
> any ideas?
>
>
>
>
Try using malloc_size(buffer)
>
>
sizeof(buffer) will return the size of the buffer variable instead.
Vince is right - sizeof(buffer) is incorrect - but I'd suggest _not_ using
mallocsize. You wont want to use that function if you're trying to write
standard C, it's one of those common to most unix functions. Also mallocsize
doesn't necessarily return the same value you passed to to the original
malloc - malloc could have tacked on a few extra bytes for it's convenience.
The best way of getting the size of a malloc-ed block IMHO is merely by
storing the requested size of that block when you malloc-ed it. You created
the memory so you should know how large the block of memory is. Just don't
discard that information.
Also consider using NSData/NSMutableData - they take the pain out of memory
allocation for you.
Jon.
P.S. Disagreeing with an apple guru. I'm going to rot in hell I know it!
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| | >Re: Malloc() (From: Vince DeMarco <email@hidden>) |