Why Does PHP's Floating-Point Arithmetic Produce Unexpected Results?

PHP Floating-Point Arithmetic Precision Discrepancies

Unlike real number arithmetic, floating-point arithmetic operates on a binary system with limited precision, resulting in approximations and inconsistencies. For instance, in PHP:

$a = '35';
$b = '-34.99';
echo ($a + $b); // Outputs 0.009999999999998

This unexpected result stems from the approximate representation of 34.99 in binary, necessitating the use of approximations. To address this issue, consider the following solutions:

• Rounding the Result: Use round($result, 2) to round the result to the desired decimal places.
• Utilizing Integers: For financial applications, store monetary values as integers (e.g., $35.00 as 3500) and perform calculations as integers before dividing by 100.

While PHP lacks a dedicated decimal datatype, adopting these approaches can mitigate the challenges associated with floating-point precision discrepancies.

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