//
// Example 4.13
// Program to print a one- or two-digit positive integer in words
//

#include <iostream>

using namespace std;

int main()
{
   void printNumber(int n);   // prototype

   int n;                     // one- or two-digit positive integer

   cout << "Enter a positive integer less than 100: ";
   cin  >> n;
   if ((n < 1) || (n > 99))
      cout << "Sorry, your number is out of range.";
   else
      printNumber(n);
   cout << endl;

   return 0;
}

//
// Function to print a positive integer in words
// Pre:  n is an integer satisfying 0 < n < 100.
// Post: n has been printed in words.
//

void printNumber(int n)
{
   void printUnits(int unitsDigit);   // prototypes
   void printTens(int tensDigit);
   void printTeens(int unitsDigit);

   int unitsDigit;                    // units digit
   int tensDigit;                     // tens digit

   unitsDigit = n % 10;
   tensDigit  = n / 10;

   if (tensDigit == 0)
      printUnits(unitsDigit);
   else if (tensDigit == 1)
      printTeens(unitsDigit);
   else
   {
      printTens(tensDigit);
      if (unitsDigit > 0)
      {
         cout << "-";
         printUnits(unitsDigit);
      }
   }
}

//
// Function to print a word for the units digit
// Pre:  unitsDigit is an integer with 0 < unitsDigit < 10.
// Post: unitsDigit has been printed in a word.
//

void printUnits(int unitsDigit)
{
   switch (unitsDigit)
   {
      case 1:  cout << "one";
               break;
      case 2:  cout << "two";
               break;
      case 3:  cout << "three";
               break;
      case 4:  cout << "four";
               break;
      case 5:  cout << "five";
               break;
      case 6:  cout << "six";
               break;
      case 7:  cout << "seven";
               break;
      case 8:  cout << "eight";
               break;
      case 9:  cout << "nine";
   }
}

//
// Function to print a word for the tens digit
// Pre:  tensDigit is an integer with 1 < tensDigit < 10.
// Post: tensDigit has been printed in a word.
//

void printTens(int tensDigit)
{
   switch (tensDigit)
   {
      case 2:  cout << "twenty";
               break;
      case 3:  cout << "thirty";
               break;
      case 4:  cout << "forty";
               break;
      case 5:  cout << "fifty";
               break;
      case 6:  cout << "sixty";
               break;
      case 7:  cout << "seventy";
               break;
      case 8:  cout << "eighty";
               break;
      case 9:  cout << "ninety";
   }
}

//
// Function to print a number in the teens using words
// Pre:  unitsDigit is an integer with 0 <= unitsDigit < 10.
// Post: Corresponding item has been printed in a word.
//

void printTeens(int unitsDigit)
{
   switch (unitsDigit)
   {
      case 0:  cout << "ten";
               break;
      case 1:  cout << "eleven";
               break;
      case 2:  cout << "twelve";
               break;
      case 3:  cout << "thirteen";
               break;
      case 4:  cout << "fourteen";
               break;
      case 5:  cout << "fifteen";
               break;
      case 6:  cout << "sixteen";
               break;
      case 7:  cout << "seventeen";
               break;
      case 8:  cout << "eighteen";
               break;
      case 9:  cout << "nineteen";
   }
}