// Fig. 6.9: GradeBook.cs
// GradeBook class uses switch statement to count letter grades.
using System;

public class GradeBook
{
   private int total; // sum of grades
   private int gradeCounter; // number of grades entered
   private int aCount; // count of A grades
   private int bCount; // count of B grades
   private int cCount; // count of C grades
   private int dCount; // count of D grades
   private int fCount; // count of F grades

   // automatic property CourseName
   public string CourseName { get; set; }

   // constructor initializes automatic property CourseName; 
   // int instance variables are initialized to 0 by default
   public GradeBook( string name )
   {
      CourseName = name; // set CourseName to name
   } // end constructor

   // display a welcome message to the GradeBook user
   public void DisplayMessage()
   {
      // CourseName gets the name of the course
      Console.WriteLine( "Welcome to the grade book for\n{0}!\n",
         CourseName );
   } // end method DisplayMessage

   // input arbitrary number of grades from user
   public void InputGrades()
   {
      int grade; // grade entered by user
      string input; // text entered by the user

      Console.WriteLine( "{0}\n{1}",
         "Enter the integer grades in the range 0-100.",
         "Type <Ctrl> z and press Enter to terminate input:" );

      input = Console.ReadLine(); // read user input

      // loop until user enters the end-of-file indicator (<Ctrl> z)
      while ( input != null )
      {
         grade = Convert.ToInt32( input ); // read grade off user input
         total += grade; // add grade to total
         ++gradeCounter; // increment number of grades

         // call method to increment appropriate counter
         IncrementLetterGradeCounter( grade );

         input = Console.ReadLine(); // read user input
      } // end while 
   } // end method InputGrades

   // add 1 to appropriate counter for specified grade
   private void IncrementLetterGradeCounter( int grade )
   {
      // determine which grade was entered
      switch ( grade / 10 )
      {
         case 9: // grade was in the 90s
         case 10: // grade was 100 
            ++aCount; // increment aCount
            break; // necessary to exit switch
         case 8: // grade was between 80 and 89
            ++bCount; // increment bCount    
            break; // exit switch
         case 7: // grade was between 70 and 79
            ++cCount; // increment cCount    
            break; // exit switch
         case 6: // grade was between 60 and 69
            ++dCount; // increment dCount    
            break; // exit switch
         default: // grade was less than 60
            ++fCount; // increment fCount       
            break; // exit switch
      } // end switch
   } // end method IncrementLetterGradeCounter

   // display a report based on the grades entered by the user 
   public void DisplayGradeReport()
   {
      Console.WriteLine( "\nGrade Report:" );

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

         // output summary of results
         Console.WriteLine( "Total of the {0} grades entered is {1}",
            gradeCounter, total );
         Console.WriteLine( "Class average is {0:F}", average );
         Console.WriteLine( "{0}A: {1}\nB: {2}\nC: {3}\nD: {4}\nF: {5}",
            "Number of students who received each grade:\n",
            aCount, // display number of A grades
            bCount, // display number of B grades
            cCount, // display number of C grades 
            dCount, // display number of D grades
            fCount ); // display number of F grades
      } // end if
      else // no grades were entered, so output appropriate message
         Console.WriteLine( "No grades were entered" );
   } // end method DisplayGradeReport
} // end class GradeBook


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