ID: 12623
Updated by: jmcastagnetto
Reported By: [EMAIL PROTECTED]
Old Status: Open
Status: Closed
Bug Type: Math related
Operating System: linux (suse)
PHP Version: 4.0.4pl1
New Comment:
The modulus operator is strictly defined for integer numbers, because it "...
basically just returns the remainder of an integer division operation ..."
(paraphrasing from the K&R book)
In this case the floats are truncated to integers and then the modulus operator is
applied, i.e.
203.5 turns into 203
17.9 turns into 17
then 203 % 17 = 16 (as expected)
Other languages follow this approach, while other round up the float previous to
operating on them, in those languages the result would be: "6"
And other languages, like Java, have a third behavior in which when using floats, a
number of integer substractions is made and a floating point reminder is calculated,
see for example: http://softwaredev.earthweb.com/multi/article/0,,12079_630791,00.html
(explanation to question 3)
BTW, gawk also performs an integer number of substractions, if you try:
gawk '{ print (203.5 % 17.9) }'
you'll get "6.6"
Bottomline, as this is an operator meant to work with integers, make the appropriate
conversion for the appropriate results, or implement a modulus function like:
function modulus_of ($q, $d) {
$rem = $q;
while ($rem > $d )
$rem -= $d;
return $rem;
}
which *will* return "6.6" for floats, and should also work on integers.
Previous Comments:
------------------------------------------------------------------------
[2001-08-07 11:14:21] [EMAIL PROTECTED]
Modulus (%) operator
i am not sure if the behavior for non-integer operands is defined, so i am not sure
how important this actually is
check
2035 % 179 = 66 // correct!
203.5 % 17.9 = 16 // incorrect - should be 6.6!
<?php
echo "2035 % 179 == " . 2035 % 179;
echo "<br>\n";
echo "203.5 % 17.9 == " . 203.5 % 17.9;
?>
------------------------------------------------------------------------
Edit this bug report at http://bugs.php.net/?id=12623&edit=1
--
PHP Development Mailing List <http://www.php.net/>
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
To contact the list administrators, e-mail: [EMAIL PROTECTED]
