Edit report at https://bugs.php.net/bug.php?id=60892&edit=1
ID: 60892
Comment by: gregs at net-virtual dot com
Reported by: gregs at net-virtual dot com
Summary: money_format returning inconsistent results
Status: Bogus
Type: Bug
Package: Math related
Operating System: OSX
PHP Version: 5.3.9
Block user comment: N
Private report: N
New Comment:
Here is another example:
php -r '$a = 70687.465 + 8.930;$b = 8.930 + 70687.465;$c =
70696.395000;printf("%f
(%.2f) %f (%.2f) %f (%.2f)\n", $a, $a, $b, $b, $c, $c);'
Previous Comments:
------------------------------------------------------------------------
[2012-01-27 04:07:18] gregs at net-virtual dot com
If anyone else runs across this, there is a good write-up here of the problem
(with some proposals to fix it):
https://wiki.php.net/rfc/rounding
My take-away is that when using %f in any of the *printf* functions (which I
presume money_format uses - what others I can only imagine), the only way to
get
true correctly rounded numbers is to explicitly round() the float before using
it.
------------------------------------------------------------------------
[2012-01-27 03:45:28] gregs at net-virtual dot com
Sorry, I meant money_format('%.2n', $float);
In all of these cases the number should be rounded to 70696.40.
------------------------------------------------------------------------
[2012-01-27 03:43:37] gregs at net-virtual dot com
With all due respect, you are not reading this.
sprintf('%.2f', $float);
number_format('%.2n', $float);
should *ROUND* these numbers, the behavior is incorrect
------------------------------------------------------------------------
[2012-01-26 22:13:57] [email protected]
Floating point values have a limited precision. Hence a value might
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly
printing it without any mathematical operations.
If you would like to know more about "floats" and what IEEE
754 is, read this:
http://www.floating-point-gui.de/
Thank you for your interest in PHP.
As you said - it's related to the way PHP (and almost all computers) store
floating point numbers.
------------------------------------------------------------------------
[2012-01-26 22:09:40] gregs at net-virtual dot com
This problem (if it is one) seems to extend to *printf* functions too:
$a = 8.930 + 70687.465;
$b = 70687.465 + 8.930;
$c = 70696.395000;
printf("A: %f, %.2f\n", $a, $a);
printf("B: %f %.2f\n", $b, $b);
printf("C: %f %.2f\n", $c , $c);'
Output:
A: 70696.395000, 70696.39
B: 70696.395000 70696.39
C: 70696.395000 70696.40
C version:
#include <stdio.h>
int main(void) {
float a, b, c, d;
a = 8.930 + 70687.465;
b = 70687.465 + 8.930;
c = 70696.395000;
printf("A: %f %.2f\n", a, a);
printf("B: %f %.2f\n", b, b);
printf("C: %f %.2f\n", c, c);
}
Output:
A: 70696.398438 70696.40
B: 70696.398438 70696.40
C: 70696.398438 70696.40
------------------------------------------------------------------------
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
https://bugs.php.net/bug.php?id=60892
--
Edit this bug report at https://bugs.php.net/bug.php?id=60892&edit=1
