Edit report at https://bugs.php.net/bug.php?id=61787&edit=1
ID: 61787
Comment by: ubuntu at spacetrace dot org
Reported by: ubuntu at spacetrace dot org
Summary: money_format round error
Status: Not a bug
Type: Bug
Package: Math related
Operating System: Linux ubuntu 11.04
PHP Version: 5.3.10
Block user comment: N
Private report: N
New Comment:
The same bug is in
sprintf("%01.2f",7.005);
which results in
7.00
while
sprintf("%01.2f",8.005);
results in
8.01
Previous Comments:
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[2012-04-26 09:38:19] ubuntu at spacetrace dot org
could you please set the Status back to "Bug"
all people i talked to, said, that this should be solved. cause it causes follow-up bugs in your
applications that are very hard to find, cause they happen so seldom
------------------------------------------------------------------------
[2012-04-22 23:15:04] ubuntu at spacetrace dot org
how does the function round(7.005,2) do the trick to get 7.01? is it so much slower than how
money_format does it?
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[2012-04-22 23:01:38] rasmus@php.net
No, that won't work. Often the value comes from expressions that always generate
lots of digits. eg. number_format('%.2i', 1/3)
What would you expect that to do? You wold get a notice every single time even
though there may not be any relevant loss of precision.
There are just certain things you need to eventually learn when you start
programming.
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[2012-04-22 22:45:48] ubuntu at spacetrace dot org
maybe an efficient way would be to see if the desired amount of digits is less than the amount of
digits in the float.
in my example where i tried to show 1.005 with only 2 fractional digits, the notice could be like:
"Error: input float exceeds maximum number of fractional digits"
this would save thousands of hours of debugging worldwide.
i am so keen on this issue, cause it cost me already about 100 hours of work to find out what was
the cause, why in my project my bills every now and then where not correctly rounded.
it is a stupid bug really hard to track and i am sure am not the only one that had this problem.
if php would throw a notice, that would save lots of hazzle for not-so-experiensed programmers.
how can you know, that you shouldn't use floats in money_format. this is a kind of secret
knowledge right now especially cause the manual says: "string money_format ( string $format ,
float $number )"
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[2012-04-22 20:40:22] rasmus@php.net
There is no efficient way to "notice the error"
If you want slow and accurate floating point manipulation it is available via the
arbitrary precision extensions like bcmath and gmp.
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