Question

I have a string which has this:

((12+41)*30)

here 12, 41 and 30 are all characters. How do I do arithmetic operations on them ?

Also when I have a number 20 how can I get a string which reads 20?

Answer 1

In order to calculate expressions like that you need create a tree of the tokens 12, +, 41, 30

                  *
                /   \
             [+]    30
            /   \
          12     41

this can be done for instance by converting your infix expression to a postfix expression, by doing so the correct operator precedence can be set. Then you go through the tree using a stack to evaluate the expression.