ID: 27744 Updated by: [EMAIL PROTECTED] Reported By: t dot steve at ariadne-quatra dot com Status: Bogus Bug Type: Math related Operating System: * PHP Version: * New Comment:
create table a ( b float,c float ); Query OK, 0 rows affected (0.11 sec) mysql> insert into a (b,c) values (141.23,141); Query OK, 1 row affected (0.07 sec) mysql> select b-c from a; +------------------+ | b-c | +------------------+ | 0.22999572753906 | +------------------+ 1 row in set (0.00 sec) Previous Comments: ------------------------------------------------------------------------ [2004-03-30 13:45:03] [EMAIL PROTECTED] That is the whole point of the answer. Floating point values are not accurate and are not nice. And we do not do a bunch of work just to make them look better in certain circumstances. ------------------------------------------------------------------------ [2004-03-30 12:07:45] garbo_doe at hotmail dot com IMHO I think this is a bug. Of course there are problems with floatingpoint values in binary form, especially when rounded many times. But in an operation like <?php echo (string)(750 - 749.99) ?> it shouldn't return "0.00999999999999" but "0.01". I did a quick test in Delphi: showmessage(floattostr(750 - 749.99)); returns "0.01, not "0.00999999999999". I had to solve it in PHP but multiplying with 100, then subtract and then divide the result by 100 again. It's not pretty :-D (0.00999[infinite 9's] IS exactly the same as 0.01, but it should remember the "infinite" with a bit or something, so (1/3)*3 = 1 and not 0.999999999) (this is similar as bug #8164) ------------------------------------------------------------------------ [2004-03-29 01:06:46] [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. Thank you for your interest in PHP. . ------------------------------------------------------------------------ [2004-03-29 01:05:32] t dot steve at ariadne-quatra dot com Description: ------------ Subtraction does not work as expected. Windows 2000 Server SP4 IIS5 PHP5RC1 Reproduce code: --------------- $result=141.23-141.00; echo $result; (or $result=141.23-141; echo $result; - same result) Expected result: ---------------- 0.23 Actual result: -------------- 0.22999999999999 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=27744&edit=1
