[Scummvm-devel] "free(0)" is valid C, and so is "delete 0;"

[Max Horn]

Am 01.08.2004 um 09:32 schrieb Eugene Sandulenko:

> Update of /cvsroot/scummvm/scummvm/saga
> In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv4757
>
> Modified Files:
> 	animation.cpp
> Log Message:
> More correct Anim destructor
>

FYI, this change is not doing anything "more correct", it produces  
identical code. The C standard specifically defines that free(0) does  
nothing. So there is no reason to checking a value for being non-NULL  
before freeing it.

To quote the POSIX docs:
"If ptr is a null pointer, no action shall occur."
(Source:  
<http://www.opengroup.org/onlinepubs/009695399/functions/free.html>)

Or to quote Microsoft:
"If memblock is NULL, the pointer is ignored and free immediately  
returns."
(Source:  
<http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ 
vccore98/html/_crt_free.asp>)

The same holds true for "delete 0;", as per the C++ specs.

Not that checking for NULL / 0 will hurt -- I just wanted to make sure  
everybody here knows it's just not needed, so that nobody starts  
converting our whole sourcebase to have checks :-)


Cheers,

Max