Posted by Tim Martin on 04/24/06 16:02

Steve wrote:
> On Fri, 21 Apr 2006 11:20:27 +0100, Tim Martin wrote:
>> Sorry, I misread you. I thought you were referring to replacing the
>> second '&', not the first one. I didn't even spot that the two boolean
>> expressions were being combined with a bitwise operator (which I agree
>> is wrong).
>>
>> For reference, the function in question was:
>>
>> function is_even($num){
>> return (is_numeric($num)&(!($num&1)));
>> }
>
> Why is it wrong? you're anding 0 or 1 with 0 or 1, and that'll return 1
> only if both are 1. It might even be faster - probably not though.

It's wrong in the sense of being a bad habit, not in the sense of
returning the wrong result. Doing this sort of thing regularly can lead
to brittle code that breaks due to seemingly innocuous changes.

Tim

[Back to original message]