Edit report at https://bugs.php.net/bug.php?id=60892&edit=1
ID: 60892 Updated by: johan...@php.net Reported by: gregs at net-virtual dot com Summary: money_format returning inconsistent results -Status: Open +Status: Bogus Type: Bug Package: Math related Operating System: OSX PHP Version: 5.3.9 Block user comment: N Private report: N 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://www.floating-point-gui.de/ Thank you for your interest in PHP. As you said - it's related to the way PHP (and almost all computers) store floating point numbers. Previous Comments: ------------------------------------------------------------------------ [2012-01-26 22:09:40] gregs at net-virtual dot com This problem (if it is one) seems to extend to *printf* functions too: $a = 8.930 + 70687.465; $b = 70687.465 + 8.930; $c = 70696.395000; printf("A: %f, %.2f\n", $a, $a); printf("B: %f %.2f\n", $b, $b); printf("C: %f %.2f\n", $c , $c);' Output: A: 70696.395000, 70696.39 B: 70696.395000 70696.39 C: 70696.395000 70696.40 C version: #include <stdio.h> int main(void) { float a, b, c, d; a = 8.930 + 70687.465; b = 70687.465 + 8.930; c = 70696.395000; printf("A: %f %.2f\n", a, a); printf("B: %f %.2f\n", b, b); printf("C: %f %.2f\n", c, c); } Output: A: 70696.398438 70696.40 B: 70696.398438 70696.40 C: 70696.398438 70696.40 ------------------------------------------------------------------------ [2012-01-26 19:24:24] gregs at net-virtual dot com Also I should add that if I do this: $a = 8.930 + 70687.465; instead of this: $a = 70687.465 + 8.930; It works. The round() function seems to behave correctly in either case. I cannot tell from this behavior if the problem is in number_format (which may not be calling round(), but doing its own flawed rounding) or if it something deeper in how PHP is storing floats/doubles. ------------------------------------------------------------------------ [2012-01-26 14:54:08] gregs at net-virtual dot com Here is a easier to read version of the test code (I also added one more): $a = 70687.465 + 8.930; $b = 70696.395; $c = 70687.464 + 8.936; $d = 70687.464 + 8.931; printf("A: %s %s %.9f\n", $a, money_format("%.2n", $a), $a); printf("B: %s %s %.9f\n", $b, money_format("%.2n", $b), $b); printf("C: %s %s %.9f\n", $c, money_format("%.2n", $c), $c); printf("D: %s %s %.9f\n", $d, money_format("%.2n", $d), $d); Output: A: 70696.395 70696.39 70696.395000000 B: 70696.395 70696.40 70696.395000000 C: 70696.4 70696.40 70696.400000000 D: 70696.395 70696.40 70696.395000000 ------------------------------------------------------------------------ [2012-01-26 14:47:43] gregs at net-virtual dot com Description: ------------ php -r '$a = 70687.465 + 8.930;$b = 70696.395;$c = 70687.464 + 8.936;printf("A: %s %s %.9f\n", $a, money_format("%.2n", $a), $a);printf("B: %s %s %.9f\n", $b, money_format("%.2n", $b), $b);printf("C: %s %s %.9f\n", $c, money_format("%.2n", $c), $c);' Output: A: 70696.395 70696.39 70696.395000000 B: 70696.395 70696.40 70696.395000000 C: 70696.4 70696.40 70696.400000000 Why is A not getting rounded up to 70696.40? Test script: --------------- php -r '$a = 70687.465 + 8.930;$b = 70696.395;$c = 70687.464 + 8.936;printf("A: %s %s %.9f\n", $a, money_format("%.2n", $a), $a);printf("B: %s %s %.9f\n", $b, money_format("%.2n", $b), $b);printf("C: %s %s %.9f\n", $c, money_format("%.2n", $c), $c);' Expected result: ---------------- A: 70696.395 70696.40 70696.395000000 B: 70696.395 70696.40 70696.395000000 C: 70696.4 70696.40 70696.400000000 Actual result: -------------- A: 70696.395 70696.39 70696.395000000 B: 70696.395 70696.40 70696.395000000 C: 70696.4 70696.40 70696.400000000 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=60892&edit=1
