Bug #79370 [Nab]: Comparison problem

Edit report at https://bugs.php.net/bug.php?id=79370&edit=1 ID: 79370 Updated by: nikic@php.net Reported by: danil at pyatnitsev dot ru Summary: Comparison problem Status: Not a bug Type: Bug Package: Variables related Operating System: Debian PHP Version: 7.4.3 Block user comment: N Private report: N New Comment: If it's any consolation, on PHP 8 this is going to print: bool(false) float(32.77) float(32.769999999999996) Which should make it more obvious what is going on here :) Previous Comments: ------------------------------------------------------------------------ [2020-03-12 09:16:28] nikic@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://www.floating-point-gui.de/ Thank you for your interest in PHP. ------------------------------------------------------------------------ [2020-03-12 09:13:50] danil at pyatnitsev dot ru Description: ------------ Incorrect comparison after addition float with integer Test script: --------------- <?php $foo = (float) 32.77; $bar = (float) 31.77; $bar += 1; var_dump($foo == $bar); // false var_dump($foo, $bar); // float(32.77) float(32.77) Expected result: ---------------- var_dump($foo == $bar); should be true in this case Actual result: -------------- It prints false ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=79370&edit=1