C++ :: Write A Calculator Using Two Stacks

I just started by defining a stack class (stackDouble). I need to write a program that accepts an infix calculator expression, with the following operators (**, exponentiation, /, division, and, -, subtraction. The operator precedence is exponent, division, and subtraction.I need to use a stack of doubles and a stack of strings, of which I can write two classes, or write a single stack template. The user will input the expression just via cin, and there will be a # before every number, a ! before each operator, and a . at the end of the expression. '#', '!', or '.' can be input into a char variable, numbers into a double variable and operators into a string variable.

For example, the following would output 6:

# 3 ! / # 2 ! / # .5 ! ** # 2 .

As stated above, I already made up a stackDouble class. What would I need to do to create the other class (I don't think I want to do it with a template)?

Code:
#include <iostream>
#include <string>
using namespace std;
class stackDouble{

[code]....