Re: while-question

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Robert Cummings schreef:
> On Mon, 2008-11-17 at 14:54 +0000, Stut wrote:
>> On 17 Nov 2008, at 14:31, Nathan Rixham wrote:
>>> if you really want a challenge try this one..
>>>
>>> task: add the numbers 5 and 17 together, using php, without using  
>>> the + operator. fill it in:
>>>
>>> function add($a , $b) {
>>> //code here but no + - / * operators
>>> return $answer;
>>> }
>>>
>>> echo add(5, 17);
>> Elemental my dear Mr Rixham...
> 
> What level is that elemental?

well it's all bitwise operating ... can't get much more
elemental that a bit in CS. but I think he meant to
say elementary (assuming the Sherlocks Holmes catchphrase)

> 
>> function add($a , $b)
>> {
>>    $answer = $a ^ $b;
>>    while (0 != ($a & $b))
>>    {
>>      $b = ($a & $b) << 1;
>>      $answer = $answer ^ $b;
>>    }
>>    return $answer;
>> }

nice, I think :P

> He only said you couldn't use the + operator... nothing was said about
> using the - operator.

<quote>
//code here but no + - / * operators
</quote>



> 
>     $total = -(-5 - 17);
> 
> Cheers,
> Rob.


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