Re: [PHP] How to convert a string into a mathematical expression?

[Chris Lambert - WhiteCrown Networks]

This would depend on the format. For example, it can't calculate "x", as its
not defined in PHP. However, you sould be able to do something like:

eval("\$math = $expression;");

...and it should work. The main problem with this is that unless you can
100% trust the user who's inputing data, its a major security problem.

If you can't, you'd have to develop your own parser for processing the data.

/* Chris Lambert, CTO - [EMAIL PROTECTED]
WhiteCrown Networks - More Than White Hats
Web Application Security - www.whitecrown.net
*/

----- Original Message -----
From: Christodoulou Demetris <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, July 13, 2001 7:09 AM
Subject: [PHP] How to convert a string into a mathematical expression?


Hi list.
 I have string variables that contain mathematical expressions. These
strings are submitted through forms.
For example if a user inserts the following-> 1+cos(0.3)*x into a text field
with name expression in an  HTML form then
what i get on the server is the string variable $expression whose values is
"1+cos(0.3)*x"

Is there a way to convert the string variable, $expression, into a
mathematical expression that can  be calculated?
 Thanks in advance.
     DX.




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