// GradeBook class that uses a 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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