note 114678 deleted from function.eval by googleguy
| From: | googleguy@php.net | Date: | Fri, 24 Feb 2017 21:12:35 +0000 |
| Subject: | note 114678 deleted from function.eval by googleguy | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-208829@lists.php.net to get a copy of this message | ||
Note Submitter: Daniele Mams
----
Modified version of sooncj answer: your regex not allow something like this: 1-(1). So I modified
your code: I change the 'Allowed PHP functions':
<?php
function calc($equation)
{
// Remove whitespaces
$equation = preg_replace('/\s+/', '', $equation);
echo "$equation\n";
$number = '(?:\d+(?:[,.]\d+)?|pi|Ï)'; // 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|Ï!', 'pi()', $equation); // Replace pi
with pi function
echo "$equation\n";
eval('$result = '.$equation.';');
}
else
{
$result = false;
}
return $result;
}
?>
This function allow also this 'strange' math function:
1) a-+b
2) a+-b
3) a++b << PHP not allow this
4) a--b. << PHP not allow this
But not allow with 3 '+' or '-':
1) a---b, a+++b, a-++b, a+--b, a+-+b, a-+-b.
Allow other Math functions.
For a++b or a--b i write another function that block that!