// Enter your name as a comment for program identification
// Program assignment Age.cpp
// Enter your class section, and time

/* The program Age.cpp prompts the user to input today's date and     
   his/her birth date, then calculates and displays the user's 
   age. The program utilizes user-defined functions.*/ 
/* Dates are entered in integer format for month and year. */ 
/* An age, described in months and years is displayed. */ 

//header files 
/* use the correct preprocessor directives for input/output */ 
#include <iostream> 
#include <string> 

using namespace std; 

// user-defined function prototypes 
/* the function getValue returns an integer value
    entered by the user in response to the prompt 
    in the string message */


/* the function getLetter returns a character value
   entered by the user in response to the prompt
   in the string message */


int main()
{
   // declare variables
   /* declare integer variables thisYear, thisMonth,
      year, month, and ageMonth and ageYear. declare a character 
      variable again to indicate if the process is
      to continue. */
   int thisYear, thisMonth, year, month, ageYear, ageMonth;
   char again = 'y';

   // display program instructions
   cout << "This program asks you to enter today's year in 4 digits,\n"
           << "and today's month number in 2 digits.\n\n"
           << "Then it asks you to enter your birth year in 4 digits\n"
           << "and your birth month in 2 digits.\n\n"
           << "The program will calculate and display your age\n"
           << "in years and months.\n";

   // assign to thisYear the value returned from a call to getValue


   // assign to thisMonth the value returned from a call to getValue 

   // loop until the user indicates to end
   while (again == 'y')
   {

      // assign to year the value returned from a call to getValue


      // assign to month the value returned from a call to getValue 


      // assign age the value of thisYear - year 
      ageYear = thisYear - year; 
      ageMonth = thisMonth - month; 
      
      /* test to see if thisMonth is less than month if true subtract 1 
         from age and add 12 to month */ 
      if (thisMonth < month)
      {
           ageYear--;
           ageMonth += 12;
      }

      // display the age in years and months
      cout << "\nYou are " << ageYear << " years and " << ageMonth
              << "months old.\n";

      // assign to 'again' the value returned from getLetter


      // convert the value of again to lowercase
      again = tolower(again);

   }

   return 0;
}



/* the function getValue returns an integer value
   entered by the user in response to the prompt 
   in the string message */
int getValue(string message)
{
   // declare variables
   // declare an integer value to enter a value
   int value;

   // prompt the user with the message passed to the function
   cout << message;

   // read in the value entered
   cin >> value;

   // return the value 
   return value;
}



/* the function getLetter returns a character value
   entered by the user in response to the prompt
   in the string message */
char getLetter(string message)
{
   // declare variables
   // declare a character value to enter a value
   char letter;

   // prompt the user with the message passed to the function
   cout << message;

   // read in the value entered
   cin >> letter;

   // return the value
   return letter;
}