#30048 [Bgs]: round() and number_format() calculates wrong

ID: 30048 Updated by: derick@php.net Reported By: joerg dot klein at ifsam dot lu Status: Bogus Bug Type: *Math Functions Operating System: win2000 PHP Version: 5.0.0 New Comment: This bug system is not the place to provide solutions, see http://php.net/support.php for that. Previous Comments: ------------------------------------------------------------------------ [2004-09-10 11:15:54] joerg dot klein at ifsam dot lu That's the cause, but not the solution. ------------------------------------------------------------------------ [2004-09-10 11:09:02] derick@php.net 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. . ------------------------------------------------------------------------ [2004-09-10 10:48:00] joerg dot klein at ifsam dot lu Description: ------------ I use a fomular as the first paramter and the result is wrong. When brackets were set, the result is correct, but this makes no sense to me. Reproduce code: --------------- echo round(0.35*90/100); echo number_format(0.35*90/100, 2, ".", ""); to get the correct result I should use the following syntax: echo round(0.35* (90/100) ) echo number_format(0.35* (90/100) , 2, ".", ""); Expected result: ---------------- 0.32 0.32 Actual result: -------------- 0.31 0.31 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=30048&edit=1