// File: prog7_1.cpp
// The user enters a non-negative decimal number and a base in the
// range 2 <= base <= 16.  A call to the function MultibaseOutput()
// displays the number in the specified base.  The program terminates
// when the user enters a number of 0 and a base 0

#include <iostream>
#include <stack>
#include <string>

using namespace std;

// output integer num in base b
string MultibaseOutput(int num, int b);

int main()
{
   int num, b;  // decimal number and base

   // prompt for a non-negative number and the desired base 2 <= B <= 16
   cout << "Enter a non-negative decimal number and base "
        << "(2 <= B <= 16)" << endl << "or 0 0 to terminate: ";
   cin >> num >> b;

   // continue until the user enters a base of 0
   while (b != 0)
   {
      cout << "    " << num << " base " << b << " is "
           << MultibaseOutput(num, b) << endl;

      cout << "Enter a non-negative decimal number and base "
           << "(2 <= B <= 16)" << endl << "or 0 0 to terminate: ";
      cin >> num >> b;
   }

   return 0;
}

string MultibaseOutput(int num, int b)
{
   // digitChar[digit] is the character that represents
   // the digit, 0 <= digit <= 15
   const string digitChar = "0123456789ABCDEF";
   string numStr;      // starts out empty

   // stack holds the base-b digits of num
   stack<char> stk;

   // extract base b digits right to left and push on stack s
   do
   {
      // push right-most digit on the stack
      stk.push(digitChar[num % b]);
      num /= b;                 // remove right-most digit from num
   } while (num != 0);          // continue until all digits found

   while (!stk.empty())         // flush the stack
   {
      numStr += stk.top();      // add digit on top of stack to numStr
      stk.pop();                // pop the stack
   }

   return numStr;
}