Hi!

I have problem with converting formula that I have as a string into formula that would give me result

f.e.
$formula="(A+B)";

and I have to get this to work f.e. like this:
replace A with 5 and B with 2 and then use it in
$c=$formula;
so $c in this example would be result of:
$c=(5+2);
$c=7;

any ideas?

http://www.php.net/manual/en/language.functions.php

PHP Code:

function formula($a,$b){
  $result=$a+$b;
  return $result;
} 


sorry, that's not it - the formula itself is INSIDE the string, so the example I wrote isn't exectly the function I will be working on

f.e. it will be something like T/4(D*D-H)
where T, D and H values are taken from other source

Then you'll have to resort either to eval() if the formula is not too complex

PHP Code:

//Be sure to have defined the value of T, and take care of precedences rules on $d*$d-$h.
//I would encapsulate them in () to be sure of that
eval("\$ret=T/4($d*$d-$h)");
echo $ret; 


or you will need to extract the datas from the string, and send them to a PHP rewritten formula.

PHP is not able to create a full formula out of a string representation.
You will have to rebuild it using PHP native functions.

ok, thanx for the tipp