#31870 [Opn->Bgs]: rounding negative numbers gives "-0"

ID: 31870 Updated by: derick@php.net Reported By: amir at foresthc dot com -Status: Open +Status: Bogus Bug Type: *General Issues Operating System: Debian woody PHP Version: 5.0.3 New Comment: This is not a discussion forum, and we just use the underlying glibc. Previous Comments: ------------------------------------------------------------------------ [2005-02-08 14:09:02] amir at foresthc dot com re-opened to get a reponse. ------------------------------------------------------------------------ [2005-02-07 13:57:34] amir at foresthc dot com I was under the impression that zero has a unique floating point representation, and the only problem is with the sign flag. Also the case at hand is not of "any mathematical operations" but of call to a mathematical function, and I am assuming there is one common piece of internal code that round() / number_format() / *printf() all use. Obviously having no familiarity with PHP's internal code my assumptions could be completely incorrect. ------------------------------------------------------------------------ [2005-02-07 13:41:29] 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. . ------------------------------------------------------------------------ [2005-02-07 13:08:49] amir at foresthc dot com Description: ------------ When rounding real negative numbers that should round to zero, the result is -0 (minus zero). This isn't a critical bug, but it's a nusanse hunting these down in places were the output reaches the user. Reproduce code: --------------- echo round(-0.1); Expected result: ---------------- 0 Actual result: -------------- -0 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=31870&edit=1