ID: 42336 Updated by: [EMAIL PROTECTED] Reported By: Makinen_Juha at hotmail dot com -Status: Open +Status: Bogus Bug Type: *Math Functions Operating System: winxp/2000 PHP Version: 5.2.3 New Comment:
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. If you would like to know more about "floats" and what IEEE 754 is read this: http://docs.sun.com/source/806-3568/ncg_goldberg.html Thank you for your interest in PHP. . Previous Comments: ------------------------------------------------------------------------ [2007-08-18 12:21:12] Makinen_Juha at hotmail dot com Round fails at 1.255, not 1.225 :) ------------------------------------------------------------------------ [2007-08-18 11:32:15] Makinen_Juha at hotmail dot com Description: ------------ In the code below, i get wrong results with php 5.2.3 and 5.2.2. The code tries to round 3 digit numbers to 2 digit numbers. Round fails at 1.225 and calculated numbers at 4.264. Iam creating a big calculating software with this language and i hope this is my mistake :) Reproduce code: --------------- <?php for ( $i=0.01;$i<10;$i=$i+0.003 ) { echo $i." -> ".calcRound( $i )."<br>"; echo round($i,2)."<br>"; } function calcRound( $inNumber ) { $intnum = $inNumber*100; $intnum = (int) $intnum; $decnum = $inNumber*100; if ( $decnum - $intnum > 0.4 ) { $intnum++; } return $intnum / 100; } ?> Expected result: ---------------- ... 1.255 -> 1.26 (calculated round) 1.26 (round function) ... ... 4.264 -> 4.26 (calculated round) 4.26 (with round function) 4.267 -> 4.27 (calculated round) ... Actual result: -------------- ... 1.255 -> 1.26 (calculated round) 1.25 (round function) ... ... 4.264 -> 4.27 (calculated round) 4.26 (with round function) 4.2670000000001 -> 4.27 (calculated round) ... ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=42336&edit=1
