Edit report at https://bugs.php.net/bug.php?id=61787&edit=1
ID: 61787
User updated 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:
money_format('%.2i',1.005) results in 1.00
and
money_format('%.2i',7.005) results in 7.01
this is definitely a bug. you only showed me, the reason, how the bug was
created. but it should still be solved!
Or, if you say, the syntax is not correct, cause you provoke an unpredictable
behaviour with '%.2i' then shouldnt that throw an error notice at least?
why cannot the php-supporters use the same algorythm, like in function round(),
where there IS rounded correctly
Previous Comments:
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[2012-04-21 21:24:35] ras...@php.net
Rounding errors compound when you loop like that. There is still no bug here.
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[2012-04-21 21:21:40] ubuntu at spacetrace dot org
now that i uderstand how floating numbers work in computers, this is sure a
real bug then:
they say:
"a tiny error in the 17th decimal place doesnât matter at all "
here the bug is at the 3rd place!
and:
" If you just donât want to see all those extra decimal places: simply
format your result rounded to a fixed number of decimal places when displaying
it."
this is what i did here and that caused the bug
think about it: NO ONE wants this behaviour if he or she uses '%.2i' in a
function
This function should be fixed, so it rounds mathematically correct like the
round() function.
If not, then it should throw an error like
"cannot shorten a float variable with this syntax" or so.
------------------------------------------------------------------------
[2012-04-21 18:17:01] ras...@php.net
How does always rounding down fix anything? What if you are trying to do 3.0
but
you actually get 2.999999999999999, if you always round down you would get 2
instead of 3.
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[2012-04-21 17:28:38] ubuntu at spacetrace dot org
ah ok,
that explains the behaviour.
wouldnt it be senseful, if php would always floor the float variable then?
or at least throw a notice error, if you parse a float through "%.2i"?
i understand this is not a senseful programm-style. cause you get an
unpredictable behaviour.
if money_format() would round down always, then it would be predictable
are there more functions that would show the same behaviour like in this
example? what about printf()
------------------------------------------------------------------------
[2012-04-21 14:59:48] ras...@php.net
Did you visit the site we provided that explains this? What you think is 7.005
is
actually represented as 7.004999999999999999 whereas 8.005 is
8.005000000000000000001
That's what limited precision means. Go read http://www.floating-point-gui.de/
for a complete explanation.
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