#47168 [Opn->Bgs]: printf of floating point variable prints maximum of 40 decimal places

ID: 47168 Updated by: iliaa@php.net Reported By: exploringbinary at gmail dot com -Status: Open +Status: Bogus Bug Type: Math related Operating System: Windows PHP Version: 5.2.8 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 PHP string formatting functions will not permit float precision beyond 40 characters, this is a hard limit. A notice was however added to indicate that this is happening. Previous Comments: ------------------------------------------------------------------------ [2009-01-20 14:55:45] exploringbinary at gmail dot com Description: ------------ printf will not print more than 40 decimal places, even if the format specifier asks for more. For example, <?php $value = 0.00000000000000011102230246251565404236316680908203125; // 2^-53 printf ("%1.53f",$value); // Prints only 40 decimal places: 0.0000000000000001110223024625156540423632 ?> Contrast this with javascript: <script type="text/javascript"> var value = 0.00000000000000011102230246251565404236316680908203125; // 2^-53 var result = value.toFixed(53); document.write (result); // Prints all 53 decimal places </script> I reported a similar bug in Visual Studio, which Microsoft acknowledged as an error: https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=329278 Reproduce code: --------------- <?php $value = 0.00000000000000011102230246251565404236316680908203125; // 2^-53 printf ("%1.53f",$value); // Prints only 40 decimal places: 0.0000000000000001110223024625156540423632 ?> Expected result: ---------------- I expect to see all 53 decimal places printed: 0.00000000000000011102230246251565404236316680908203125 Actual result: -------------- Only 40 decimal places are printed: 0.0000000000000001110223024625156540423632 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=47168&edit=1