SOURCE FILE: 6.09ReverseNum.cpp

//   
// Example 6.09. Program to print the digits of a    
// nonnegative input integer in reverse order   
//    
   
#include <iostream.h>
   
int main(void)   
{   
   int ReadNum(void);   
   void PrintReverse(int num);   
   
   int num;             // nonnegative input integer 
   
   num = ReadNum();   
   PrintReverse(num);   
   
   return 0;
}   
   
//   
// Function to print instructions and repeatedly read   
// integers until the user enters a nonnegative integer,   
// which the function returns   
// Pre:  none   
// Post: A nonnegative integer has been returned.   
//    
   
int ReadNum(void)   
{   
   int num;             // nonnegative input integer 
   
   cout << "This program prints a nonnegative integer backwards.\n\n";
   
   do   
   {   
      cout << "Enter a nonnegative integer: ";
      cin  >> num;
   }   
   while (num < 0);   
   
   return num;   
}   
   
   
//   
// Function to print the digits of a nonnegative integer   
// in reverse order.   
// Pre:  num is a nonnegative integer.   
// Post: The digits of num have been displayed in reverse order.   
//    
   
void PrintReverse(int num)   
{   
   int RightmostDigit; // rightmost digit of num 
   
   cout << num << " backwards is ";
   do   
   {   
      RightmostDigit = num % 10;      
      cout << RightmostDigit;
      num /= 10;   // move next digit into rightmost position 
   }   
   while (num > 0);      
   
   cout << endl;
}