C++ Carrano infix calculator with stacks

I'm working on a infix calculator for one of my classes and I'm fairly new to stacks and such and I have hit a wall when its comes to implementing the execution of the operations of the values. The function used for executing only receives a operator and one value parameter, so I'm lost as to how to perform the operations on a value when I need two. I am basing my code off of pseudo-code that was supplied by the professor (This is a picture of it). If anyone could point me in the right direction I'd appreciate it. This is what I have.

int main()
{
    stack<char> op;
    stack<int>  val;

        int result;
        char ch;

        cin >> ch;

        while (ch != 'Q') //Once it reads 'Q' the program quits
        {
            switch (ch)
            {
                case '0': case '1': case '2': case '3': case '4':
                case '5': case '6': case '7': case '8': case '9':
                    val.push(ch);
                    break;

                case '(':
                    op.push(ch);
                    break;

                case '+': case '-': case '*': case '/':
                    if (op.empty())
                    {
                        op.push(ch);
                    }
                    else if (Precedence(ch) > Precedence(op.top()))
                    {
                        op.push(ch);
                    }
                    else
                    {
                        while ( (!op.empty()) && (Precedence(ch) <=         Precedence(op.top())) )
                        {
                            Execute(op, val);
                        }
                        op.push(ch);
                    }
                    break;

                case ')':
                {
                    while (op.top() != '(')
                    {
                        Execute(op, val);
                    }
                    op.pop();
                    break;
                }
            }

            cin >> ch;
        }

        while (!op.empty())
        {
            Execute(op, val);
        }
        val.top(result);

        return 0;
    }


int Precedence(char oper)
{
    if (     oper=='*' || oper=='/')
        return 2;
    else if( oper=='+' || oper=='-')
        return 1;
    else
        return 0;
}

void Execute(stack<char>& op, stack<int>& val)
{
    switch (op)
    {
        case '+':
            result = val + val; //Unsure how to get results
            break;

        case '-':
            result = val - val; //Unsure how to get results
            break;

        case '*':
            result = val * val; //Unsure how to get results
            break;

        case '/':
            result = val / val; //Unsure how to get results
            break;
    }

    return result;

}