realloc, does it copy?

f0rmula · 03-22-2005, 01:55 PM

If it's not able to expand my current allocation, and has to create a different larger allocation, is the contents of the existing smaller allocation copied to the beginning of the new allocation?

I've read this but still unsure..

http://www.opengroup.org/onlinepubs/...h/realloc.html

Thanks

James

drisay · 03-22-2005, 02:01 PM

my understanding is yes

TheLinuxDuck · 03-22-2005, 02:09 PM

Yes, realloc retains the contents of the item of which memory is reallocated.

From the realloc man page:

Quote:

realloc() changes the size of the memory block pointed to by ptr to size bytes. The contents will be unchanged to the minimum of the old and new sizes; newly allocated memory will be ininitialized.

and

Quote:

realloc() returns a pointer to the newly allocated memory, which is suitably aligned for any kind of variable and may be different from ptr, or NULL if the request fails. If size was equal to 0, either NULL or a pointer suitable to be passed to free() is returned. If realloc() fails the original block is left untouched - it is not freed or moved.

f0rmula · 03-22-2005, 02:30 PM

Brilliant.. thanks..

God know's why I didn't check the man page.. apologies..

James

TheLinuxDuck · 03-22-2005, 02:55 PM

(= No worries.