From: Ashley Sheridan
To: cr.vege...@gmail.com
Cc: php-general@lists.php.net
Sent: Thursday, April 15, 2010 10:08 AM
Subject: Re: [PHP] changing NULL behavior in PHP arithmetic
On Thu, 2010-04-15 at 09:46 +0200, cr.vege...@gmail.com wrote:
Hi All,
Is there an option in PHP to change the behavior of NULL in PHP functions ?
Now PHP uses NULL as a 0 (zero) for arithmetic, for example:
NULL + 6 = 6
NULL * 6 = 0
NULL / 6 = 0
6 / NULL = Division by zero
What I need is the same behavior as #N/A (or =NA()) in Excel, where:
#N/A + 6 = #N/A
#N/A * 6 = #N/A
#N/A / 6 = #N/A
6 / #N/A = #N/A
because arithmetic operations with "Unknown" operands should result to
"Unknown" ...
TIA, Cor
You can't really, because PHP is a loosely typed language, which means it
silently converts values as required by the situation. When you use
mathematical operators, PHP converts the values to numbers, and NULL maps to a
0 (as does the boolean false and an empty string)
The only way I can see to fix your problem is to check the value of the
variables you are working on with something like is_int()
Thanks,
Ash
http://www.ashleysheridan.co.uk
Thanks for replying.
I tried the predefined PHP constant NAN.
However, NAN + 6 = 6, so NAN is can't be used either.
To bypass the problem, I now use is_null().
is_int() can also be used, but does it have advantages over is_null() ?
Thanks, Cor
