// Enter a grade which is 1 and 100 for user.
#include <iostream>
using std::cin; 
using std::cout;
using std::endl;
using std::cerr;
 
#include <cstdlib>
using std::rand;
 
#include <ctime>
 
void grade();
 
bool isCorrect( int, int ); // function
 
int main();
{
   // srand( time( 0 ) ); // seed random number generator
   grade(void);
 
   return 0; // termination
 
} // end main
 
// grade generates numbers between 1 and 100
// and checks grade
void grade()
{
   int answer; // randomly generated number
   int guess; // grade entered
   char response; // 'y' or 'n'
 
   do{
      // generate random number between 1 and 100
      // 1 is shift, 100 is scaling factor
      answer = 1 + rand() % 100;
 
      // prompt for grade
      cout << "Enter number between 1 and 100.\n" 
           << "Enter Grade?\n" << endl << "? ";
 
      cin >> guess;
 
      // loop until correct number
      while ( !isCorrect( guess, answer ) ) 
         cin >> guess;      
 
      // prompt for another grade
      cout << "\nExcellent! The grade is !\n"
           << "Would you like to enter a grade again (y or n)? ";
      cin >> response;
 
      cout << endl;
   } while ( response == 'y' );
}// end function grade
 
// isCorrect returns true if g equals a
// if g does not equal a, displays hint
bool isCorrect( int g, int a )
{
   // grade is correct
   if ( g == a )
      return true;
 
   // grade is incorrect; display hint
   if ( g < a )
      cout << "Grade is to low. Try again.\n? ";
   else
      cout << "Grade is to high. Try again.\n? ";
 
   return false;
} // end function isCorrect