#43487 [Opn->Bgs]: Wrong conversion of float to string

ID: 43487 Updated by: johannes@php.net Reported By: jm at wo dot cz -Status: Open +Status: Bogus Bug Type: Strings related Operating System: Linux PHP Version: 5.2.5 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: ------------------------------------------------------------------------ [2007-12-03 16:53:25] jm at wo dot cz Description: ------------ Some float numbers are incorrectly converted to string values: I found it by playing with eval and getting wrong results. Then I did: echo floatval('3.86e-6'); // output: 3.86E-6 echo floatval('1.01e-6'); // output: 1.01E-6 But echo floatval('1E-6'); // output: :.0E-7 But one can do: $f=1E-6; echo $f; // output: .0E-7 So it must be a problem with float to string conversion. Reproduce code: --------------- $f=1E-6; echo $f; // output: :.0E-7 Expected result: ---------------- 1.0E-6 Actual result: -------------- :.0E-7 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=43487&edit=1