#25562 [Opn->Bgs]: Float to String to Float conversion error

ID: 25562 Updated by: helly@php.net Reported By: daseymour at 3hc dot org -Status: Open +Status: Bogus Bug Type: Math related Operating System: [Win 2000 SP4] and [Win XP SP1] PHP Version: 4.3.3 New Comment: Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php Floating point values are handled with a limited precision. Previous Comments: ------------------------------------------------------------------------ [2003-09-16 15:34:29] daseymour at 3hc dot org Description: ------------ When I convert a large float value to a string and then back to a float, the original and the resulting values are not equal. Note: I looked for this error in the bug list, but did not find one with the current stable release of PHP (4.3.3). Thanks in advance. Reproduce code: --------------- // Create some large number $testStart = (float) unserialize("d:1125899906842624;"); // Output value echo "Before string conversion: $testStart <br>\n"; // Convert value to string $testString = (string) $testStart; // Output string echo "After string conversion: $testString <br>\n"; // Convert string back to a value $testEnd = (float) $testString; // Output value echo "After float conversion: $testEnd <br>\n"; // Compare the two values if( $testStart == $testEnd ) { echo "<br>\nThe two values are equal.<br>\n"; } else { echo "<br>\nThe two values appear to be the same, but are <u>not</u> equal!<br>\n"; }; Expected result: ---------------- I expect to see "The two values are equal." Actual result: -------------- I am getting "The two values appear to be the same, but are not equal!" ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=25562&edit=1