NULL vs 0
On 09/20/2010 11:24 PM, Amos Jeffries wrote: On Mon, 20 Sep 2010 17:44:17 -0600, Alex Rousskov wrote: It is best to use 0 in C++ programs, but we have too much NULL-using code to fight. Easy enough to fix with a grep/sed. Do we make '0' a coding style requirement? Yes, we should if there are no objections. However, replacing current NULLs will invalidate most pending patches. I would not do it proactively to the old code. The 'NULL not always 0' is relevant to Win32 builds with MS Visual Studio which sets NULL == 0xCDCDCDCD (the kernels invalid RAM pattern, somewhere out in invalid memory space). I'm not sure if the newer VS still do this. Squid will most likely not work if NULL is not false. 0xCDCDCDCD is not false. Consider: some_pointer = some_function_that_may_return_NULL(); if (!some_pointer) ... Cheers, Alex.
Re: NULL vs 0
On Wed, Sep 22, 2010 at 4:58 AM, Alex Rousskov rouss...@measurement-factory.com wrote: Squid will most likely not work if NULL is not false. 0xCDCDCDCD is not false. Consider: some_pointer = some_function_that_may_return_NULL(); if (!some_pointer) ... When compilers do that, they also translate the if expression appropriately. But they are also meant to handle NULL vs 0 transparently in that case, AIUI. -Rob
Re: NULL vs 0
On 09/21/2010 12:49 PM, Robert Collins wrote: On Wed, Sep 22, 2010 at 4:58 AM, Alex Rousskov rouss...@measurement-factory.com wrote: Squid will most likely not work if NULL is not false. 0xCDCDCDCD is not false. Consider: some_pointer = some_function_that_may_return_NULL(); if (!some_pointer) ... When compilers do that, they also translate the if expression appropriately. But they are also meant to handle NULL vs 0 transparently in that case, AIUI. Scary but good to know, thank you. Looks like 0xCDCDCDCD, if used as a pointer, becomes false in that case! Alex.
