PHP7 Mining Pit: Floating-point data comparison

Today, a strange problem is encountered in the project, and the result is a comparison of two variables with equal values for the computed double type of the variable, but the results are not equal.

<?php$a=42735.04; $b =17806.2; $c = $a/36; $c =round ($c, 2); $d = $c *15;echo ' $b value is: '. $b. " \ n "; Echo ' $d value is: '. $d. " \ n ", if ($b = = $d) {echo" ok\n ";} else{echo "sorry\n";}

The results are as follows, the value of two variables is the same, do ' = = ' comparison operation but return false

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The reason is that the precision has changed after a series of operations such as/,*,round () in the floating-point numbers in PHP7.


Solution: Compare any variable of any precision as a string.

A better solution has been provided in the PHP7.

(PHP 4, PHP 5, PHP 7) bccomp-compare two arbitrary-precision numeric descriptions int Bccomp (string $left _operand, String $right _operand[, int $scale = int]) Compares Right_operand and Left_operand, and returns the result of an integer.

Finally use Bccomp () to compare and resolve the problem

if (Bccomp (String) $b, (String) $d, 2) = = = 0) {echo "Yes \ n";} else{echo "no \ n";}

This article is from the "My PHP path" blog, so be sure to keep this source http://phpme.blog.51cto.com/663593/1947237

PHP7 Mining Pit: Floating-point data comparison