[RESOLVED] eval function help

niroshan

Hi guys,

Is there anyway I can process and output a result, evaluating a condition which is given in a string??
ok let me explain,

Initially what happen is all my formulas (conditions) will be entered from the back end of my system. so from the front end if some user select a particular formula the system should be able to grab that data from the database (which is return as a string) and process it and out put only the result to the user.

here is an example what i did:

//backend formula 
//------------------------

//formula name : ADD
$formula = '$a + $b';


//front end user select the formula 'ADD'
//------------------------------------------------

//assigning values to $aa and $bb
$aa=5;
$bb=6;

$databaseStr = '$a + $b'; //fetched from the database

eval("\$xx = \"$databaseStr \";");

print $xx;

but the result was,

//out put from above code
5 + 6

I dont want this. What i want is to PHP to assign those variables to $aa and $bb and process it (add them according to this formula) and return the out put. so as for the above formula it should return me 11 not 5 + 6.

Can I do this?

Thanks in advance,

Regards,
niroshan

NogDog

eval("\$xx = $databaseStr;");

However, as eval() is a bit clunky and potentially dangerous (if anybody is able to pollute the data source with malicious code), I'd recommend rethinking the application design to not use eval(), if possible.

niroshan

Hi NogDog,

Thank you so much for your reply. This will do the trick for me.

Thanks for the advice but as for my system, formulas will only have conditions. they will not have any mathematical calculations and i wont be updating my database values after executing the eval function according to the return values. but really appreciate your advice.

Regards,
niroshan