@ 2014-01-10T21:10:45Z <?php
$test = '2+3*pi';
// Remove whitespaces
$test = preg_replace('/\s+/', '', $test);
$number = '(?:\d+(?:[,.]\d+)?|pi|π)'; // What is a number
$functions = '(?:sinh?|cosh?|tanh?|abs|acosh?|asinh?|atanh?|exp|log10|deg2rad|rad2deg|sqrt|ceil|floor|round)'; // Allowed PHP functions
$operators = '[+\/*\^%-]'; // Allowed math operators
$regexp = '/^(('.$number.'|'.$functions.'\s*\((?1)+\)|\((?1)+\))(?:'.$operators.'(?2))?)+$/'; // Final regexp, heavily using recursive patterns
if (preg_match($regexp, $q))
{
$test = preg_replace('!pi|π!', 'pi()', $test); // Replace pi with pi function
eval('$result = '.$test.';');
}
else
{
$result = false;
}
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Output for 8.1.0 - 8.1.28 , 8.2.0 - 8.2.18 , 8.3.0 - 8.3.6 Warning: Undefined variable $q in /in/hmWEd on line 12
Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in /in/hmWEd on line 12
Output for 8.0.0 - 8.0.30 Warning: Undefined variable $q in /in/hmWEd on line 12
Output for 5.0.4 - 5.0.5 , 5.1.0 - 5.1.6 , 5.2.0 - 5.2.17 , 5.3.0 - 5.3.29 , 5.4.0 - 5.4.45 , 5.5.0 - 5.5.38 , 5.6.0 - 5.6.28 , 7.0.0 - 7.0.20 , 7.1.0 - 7.1.25 , 7.2.0 - 7.2.33 , 7.3.0 - 7.3.31 , 7.4.0 - 7.4.25 , 7.4.27 - 7.4.33 Notice: Undefined variable: q in /in/hmWEd on line 12
Output for 7.3.32 - 7.3.33 , 7.4.26 Output for 4.3.0 - 4.3.11 , 4.4.0 - 4.4.9 , 5.0.0 - 5.0.3 Notice: Undefined variable: q in /in/hmWEd on line 12
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241.18 ms | 402 KiB | 372 Q