Stack questions

[manonthem00n]

I need to finish "int evaluate(string exp)" What am I missing to return the proper results? For example I need (((1+2)/3)*(6-4)) to return 2.

//The evaluate function takes a string containing an arithmetic expression,
//evaluates it,and returns its result
int evaluate(string exp)
 {
 stack<char> parStack;
 stack<int> numStack;
 stack<char> opStack;

 int j = exp.size();
 int i=0;
 char x;


 while (i<j)
 {
     if(exp[i] == '(')
     {
         parStack.push(exp[i]);
         cout << exp[i] << endl;
     }
     if((exp[i]=='0') || (exp[i]=='1') || (exp[i]=='2') || (exp[i]=='3') || (exp[i]=='4') || (exp[i]=='5') || (exp[i]=='6') || (exp[i]=='7') || (exp[i]=='8') || (exp[i]=='9'))
     {
         numStack.push(exp[i]);
     }
     if((exp[i] == '+') || (exp[i] == '-') || (exp[i] == '*') || (exp[i] == '/') || (exp[i] == '%'))
     {
         opStack.push(exp[i]);
     }
     i++;
 }

return 0;


 }