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[QUOTE="scatello, post: 11302, member: 1949"]
Quelle: [URL]https://stackoverflow.com/questions/18880772/calculate-math-expression-from-a-string-using-eval[/URL]
[CODE=php]<?php
class Field_calculate {
    const PATTERN = '/(?:\-?\d+(?:\.?\d+)?[\+\-\*\/])+\-?\d+(?:\.?\d+)?/';

const PARENTHESIS_DEPTH = 10;

public function calculate($input){
        if(strpos($input, '+') != null || strpos($input, '-') != null || strpos($input, '/') != null || strpos($input, '*') != null){
            //  Remove white spaces and invalid math chars
            $input = str_replace(',', '.', $input);
            $input = preg_replace('[^0-9\.\+\-\*\/]', '', $input);

//  Calculate each of the parenthesis from the top
            $i = 0;
            while(strpos($input, '(') || strpos($input, ')')){
                $input = preg_replace_callback('/$([^\($]+)\)/', 'self::callback', $input);

$i++;
                if($i > self::PARENTHESIS_DEPTH){
                    break;
                }
            }

//  Calculate the result
            if(preg_match(self::PATTERN, $input, $match)){
                return $this->compute($match[0]);
            }
            // To handle the special case of expressions surrounded by global parenthesis like "(1+1)"
            if(is_numeric($input)){
                return $input;
            }

return 0;
        }

return $input;
    }

private function compute($input){
        $compute = create_function('', 'return '.$input.';');

return 0 + $compute();
    }

private function callback($input){
        if(is_numeric($input[1])){
            return $input[1];
        }
        elseif(preg_match(self::PATTERN, $input[1], $match)){
            return $this->compute($match[0]);
        }

return 0;
    }
}

// ********************************* Ab hier deine Sachen *******************************
$massX = "(#-32-16)/2";

$mass = 1200;

if(strpos($massX,"#") !== false)
{
  
   $formel = $massX;
   $formel = str_replace("#", $mass, $formel);
  
   $Cal = new Field_calculate();

$fertigmass1 = $Cal->calculate($formel);

echo $formel . " > " . $fertigmass1;
}
?>[/CODE]
[/QUOTE]

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