Joonake

Tried to search but dont find anything. I just cant find proper keywords for this :'(

Hello all, I have a problem when I am trying to create calculator with PHP. I have created form that you can use to add numbers and operations to input field, but I just cant figure out how to "calculate" the calculation that is stored in variable. For example: $expression = "5"; $expression .= "+"; $expression .= "5"; $answer = $expression; This way I get just the "5+5" on $answer, but I would like to get "10". I dont want to write my own function to parse the calculation because I know that it exists, just dont know how this is done. I have tried to use printf but it wont help. Anyone can help me?