Calculate a sum in a string

Question

I have string like this: $string = \"a + b + c\";. Now I would like to calculate the string as sum.

For example:

$a = 10;
$b = 10;
$c =          


        

Answer 1

My standard answer to this question whenever it crops up:

Don't use eval (especially as you're stating that this is user input) or reinvent the wheel by writing your own formula parser.

Take a look at the evalMath class on PHPClasses. It should do everything that you're asking, in a safe sandbox.