Posted by The Natural Philosopher on 02/02/08 00:14

bill wrote:
> Jerry Stuckle wrote:
>> The Natural Philosopher wrote:
>>> Jerry Stuckle wrote:
>>>> The Natural Philosopher wrote:
>>>>> Rik Wasmus wrote:
>>>>>> On Fri, 01 Feb 2008 16:59:18 +0100, The Natural Philosopher
>>>>>> <a@b.c> wrote:
>>>>>>> The question says it all.
>>>>>>>
>>>>>>> I have an input box, which I fill in with a price.
>>>>>>> IOt gets passed to the main form as a variable, then shoved into
>>>>>>> an SQL field vue a print '%d' statement where the argument is
>>>>>>> $price*100.
>>>>>>
>>>>>> Could you give us the exact code & input values? And what database
>>>>>> (&version) are you using?
>>>>>>
>>>>>>> For some reaosn, this particular value goes to 6998.
>>>>>>>
>>>>>>> If I update hee database manually to 6999, it displays as 69.99.
>>>>>>>
>>>>>>> If I enter 69.999 it updates as 6999..not 69999
>>>>>>
>>>>>> Seems to have something to do with float/double precision.
>>>>>> However, the precision isn't that big, and I cannot reproduce it
>>>>>> in PHP 5.2 here..
>>>>>>
>>>>>> PHP5.2.4:
>>>>>> <?php echo 69.99*100 ?> => output 6999
>>>>>> MySQL5.0.45-community-nt:
>>>>>> SELECT CAST(69.99*100 AS UNSIGNED); => 6999
>>>>>
>>>>> Rik. Its worse than that NOTHING to do with databases.
>>>>>
>>>>> Here is a code fragment.
>>>>>
>>>>> echo $sale_price."<br>\r\n"; // gives 69.99
>>>>> printf ("%d<br>\r\n",($sale_price*100)); //gives 6998
>>>>> $xxx=$sale_price*100;
>>>>> echo $xxx."<br>\r\n"; // gives 6999
>>>>> printf ("%d<br>\r\n",$xxx); //gives 6998
>>>>>
>>>>>
>>>>> Now $sale_price comes from a text type input via a _POST_ variable,
>>>>> so I guess its 'text' as its raw form PHP invisible casting drives
>>>>> me nuts, so you can tell ME what $xxx is...
>>>>>
>>>>
>>>> According to the PHP manual:
>>>>
>>>> %d - the argument is treated as an integer, and presented as a
>>>> (signed) decimal number.
>>>>
>>>> Which means it is truncating instead of rounding.
>>>>
>>>> 69.99 is not exact. It's approximately 69.98999999999999488409.
>>>>
>>>> So 69.99*100 comes out to be 6998.999999999999488409 and truncated
>>>> you get 6998.
>>>>
>>> Right. So every other php funtion treats 6999 as 6999,. except
>>> printf's %d.
>>>
>>> If you use %s, it works..
>>>
>>> Invisible casting has to be the worst thing ever. That's WHY I did it
>>> all in cents (or pence)to avoid these pissing float issues.
>>>
>>> Is there a function that takes 69.99*100 and makes it a properly
>>> rounded integer?
>>>
>>>
>>>
>>>
>>>
>>>
>>
>> round().
>>
> A bit verbose, don't you think, Jerry ? <g>
Yeah, but it works.

Jeesh.
I've gotta lotta code to patch.

[Back to original message]