Bug #52894 [Bgs]: number_format fails with large values

Edit report at http://bugs.php.net/bug.php?id=52894&edit=1 ID: 52894 Updated by: rasmus@php.net Reported by: info at tellmatic dot org Summary: number_format fails with large values Status: Bogus Type: Bug Package: *Math Functions Operating System: linux PHP Version: 5.2.14 Block user comment: N New Comment: Yes, that is all number_format does. But, you asked it for 50 digits of precision for 1234.560000 which just isn't possible for computers to represent given the way they they handle floating point numbers. It has nothing to do with number_format. You will see the same if you do: ini_set('precision',50); echo 1234.560000; If you need super-precise floating point, you can't use the computers built-in floating point support. You will need to use http://php.net/gmp instead. The big drawback is that it is much much slower than the computer's native floating point support. Previous Comments: ------------------------------------------------------------------------ [2010-09-21 14:48:49] info at tellmatic dot org number_format should 'format' numbers, not recalculate, or? thats how i understand the function. ------------------------------------------------------------------------ [2010-09-20 18:24:37] rasmus@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. 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. . ------------------------------------------------------------------------ [2010-09-20 17:53:57] info at tellmatic dot org Description: ------------ wrong output, not as give, drifts a lot! Test script: --------------- number_format("1234.560000", 50, '.', ''); Expected result: ---------------- expected output should be 1234.56 with additional 48 zeros! and not a 'random value'. Actual result: -------------- == 1234.55999999999994543031789362430572509765625000000000 ???? can't be! ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52894&edit=1