// fig04_06.cpp
// Using a switch statement to count letter grades.
#include <iostream>
#include <iomanip>
using namespace std;

int main() {
   int total{0}; // sum of grades                  
   int gradeCounter{0}; // number of grades entered
   int aCount{0}; // count of A grades             
   int bCount{0}; // count of B grades             
   int cCount{0}; // count of C grades             
   int dCount{0}; // count of D grades             
   int fCount{0}; // count of F grades             

   cout << "Enter the integer grades in the range 0-100.\n"
      << "Type the end-of-file indicator to terminate input:\n"
      << "   On UNIX/Linux/macOS type <Ctrl> d then press Enter\n"
      << "   On Windows type <Ctrl> z then press Enter\n";

   int grade;

   // loop until user enters the end-of-file indicator
   while (cin >> grade) {
      total += grade; // add grade to total
      ++gradeCounter; // increment number of grades
      
      //  increment appropriate letter-grade counter   
      switch (grade / 10) {                                                
         case 9:  // grade was between 90              
         case 10: // and 100, inclusive                
            ++aCount;         
            break; // exits switch         
                                                       
         case 8: // grade was between 80 and 89        
            ++bCount;            
            break; // exits switch                      
                                                       
         case 7: // grade was between 70 and 79        
            ++cCount;            
            break; // exits switch                      
                                                       
         case 6: // grade was between 60 and 69        
            ++dCount;             
            break; // exits switch                      
                                                       
         default: // grade was less than 60            
            ++fCount;              
            break; // optional; exits switch anyway
      } // end switch                                  
   } // end while 

   // set floating-point number format
   cout << fixed << setprecision(2);

   // display grade report
   cout << "\nGrade Report:\n";

   // if user entered at least one grade...
   if (gradeCounter != 0) {
      // calculate average of all grades entered
      double average{static_cast<double>(total) / gradeCounter};

      // output summary of results
      cout << "Total of the " << gradeCounter << " grades entered is " 
         << total << "\nClass average is " << average  
         << "\nNumber of students who received each grade:"
         << "\nA: " << aCount << "\nB: " << bCount << "\nC: " << cCount
         << "\nD: " << dCount << "\nF: " << fCount << "\n"; 
   } 
   else { // no grades were entered, so output appropriate message
      cout << "No grades were entered" << "\n";
   }
}


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