note 114916 deleted from function.eval by googleguy

Note Submitter: andrea at donboscoland dot it ---- Modified version of Daniele Mams's answer: I change the $number definition to accept scientific notation like in: http://stackoverflow.com/questions/638565/parsing-scientific-notation-sensibly <?php function calc($equation) { // Remove whitespaces $equation = preg_replace('/\s+/', '', $equation); echo "$equation\n"; $number = '(-?(?:0|[1-9]\d*)(?:\.\d*)?(?:[eE][+\-]?\d+)?)'; // What is a number $functions = '(?:abs|atan|ceil|cos|exp|gmp_fact|intval|log(10)?|rand|round|sin|sqrt|tan)'; // Allowed PHP functions $operators = '[\/*\^\+-]'; // Allowed math operators $regexp = '/^([+-]?('.$number.'|'.$functions.'\s*\((?1)+\)|\((?1)+\))(?:'.$operators.'(?1))?)+$/'; // Final regexp, heavily using recursive patterns if (preg_match($regexp, $equation)) { $equation = preg_replace('!pi|π!', 'pi()', $equation); // Replace pi with pi function echo "$equation\n"; eval('$result = '.$equation.';'); } else { $result = false; } return $result; } ?>