operands

While using stacks and queues, how would I go about using an if statement that is asking whether or not that first object in a line (in a queue) is an operand? What do I use to define an operand? In my pseudo code I have just written:

if operand
  move to q2
else
 *a bunch of other rules*

So I'm not sure how to translate the operand into syntex.

Edit (Jan. 30th, 11:02pm):
I finally got it compiling and running; It is "sort of" doing what it is suppose to, just not correctly. It's not producing the correctly ordered postfix, but it does recieve and print out something, so yay for now:

#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
#include <iomanip>
#include <stack>
#include <queue>
#include <cctype>

using namespace std;

int operatorPrecedence(char ch);

int main()
{
  ifstream ifp;
  string fileRead;

  stack<char> aStack;
  queue<char> q1;
  queue<char> q2;

  cout << "Name of file to be read." << endl;
  cin >> fileRead;

  ifp.open(fileRead.c_str());

  if (!ifp.fail())
    {
      while(!ifp.eof())
        {
          char ch;
          ifp.get(ch);
          while(ch != '\n')
            {
              cout << "ch: " << ch << endl;
              q1.push(ch);
              ifp.get(ch);
            }
          while(!q1.empty())
            {
              if (isalpha(q1.front()))
                {
                  q2.push(q1.front());
                  q1.pop();
                }
              else
                if (aStack.empty())
                  {
                    aStack.push(q1.front());
                    q1.pop();
                  }
                else if (operatorPrecedence(ch) == 1)
                  {
                    q2.push(q1.front());
                    q1.pop();
                  }
                else if (operatorPrecedence(ch) == 2)
                  {
                    aStack.push(q1.front());
                    q1.pop();
                  }
                else
                  {
                    q2.push(q1.front());
                    q1.pop();
                  }
            }
          while(!aStack.empty())
            {
              q2.push(aStack.top());
              aStack.pop();
            }
          cout << "The post fix answer is: ";
          while(!q2.empty())
            {
              cout << q2.front();
              q2.pop();
            }
          cout << endl;
        }
      ifp.close();
    }
  else
    cout << "Error opening file." << endl;

  return 0;
}

int operatorPrecedence(char ch)
{
  switch (ch)
    {
    case '*':
      return 2;
    case '/':
      return 2;
    case '+':
      return 1;
    case '-':
      return 1;
    }
  return 0;
}