1   // Fig. 7.15: GradeBook.h
 2   // Definition of class GradeBook that uses an array to store test grades.
 3   // Member functions are defined in GradeBook.cpp
 4   #include <string>
 5   #include <array>
 6
 7   // GradeBook class definition
 8   class GradeBook
 9   {
10   public:
11      // constant -- number of students who took the test
12      static const size_t students = 10; // note public data
13
14      // constructor initializes course name and array of grades
15      GradeBook( const std::string &, const std::array< int, students > & );
16
17      void setCourseName( const std::string & ); // set the course name
18      string getCourseName() const; // retrieve the course name
19      void displayMessage() const; // display a welcome message
20      void processGrades() const; // perform operations on the grade data
21      int getMinimum() const; // find the minimum grade for the test
22      int getMaximum() const; // find the maximum grade for the test
23      double getAverage() const; // determine the average grade for the test
24      void outputBarChart() const; // output bar chart of grade distribution
25      void outputGrades() const; // output the contents of the grades array
26   private:
27      std::string courseName; // course name for this grade book
28      std::array< int, students > grades; // array of student grades
29   }; // end class GradeBook

 1   // Fig. 7.16: GradeBook.cpp
 2   // GradeBook class member functions manipulating
 3   // an array of grades.
 4   #include <iostream>
 5   #include <iomanip>
 6   #include "GradeBook.h" // GradeBook class definition
 7   using namespace std;
 8
 9   // constructor initializes courseName and grades array
10   GradeBook::GradeBook( const string &name,
11      const array< int, students > &gradesArray )
12      : courseName( name ), grades( gradesArray )
13   {
14   } // end GradeBook constructor
15
16   // function to set the course name
17   void GradeBook::setCourseName( const string &name )
18   {
19      courseName = name; // store the course name
20   } // end function setCourseName
21
22   // function to retrieve the course name
23   string GradeBook::getCourseName() const
24   {
25      return courseName;
26   } // end function getCourseName
27
28   // display a welcome message to the GradeBook user
29   void GradeBook::displayMessage() const
30   {
31      // this statement calls getCourseName to get the
32      // name of the course this GradeBook represents
33      cout << "Welcome to the grade book for " << getCourseName() << "!"
34         << endl;
35   } // end function displayMessage
36
37   // perform various operations on the data
38   void GradeBook::processGrades() const
39   {
40      // output grades array
41      outputGrades();
42
43      // call function getAverage to calculate the average grade
44      cout << setprecision( 2 ) << fixed;
45      cout << " Class average is " << getAverage() << endl;
46
47      // call functions getMinimum and getMaximum
48      cout << "Lowest grade is " << getMinimum() << " Highest grade is "
49         << getMaximum() << endl;
50
51      // call function outputBarChart to print grade distribution chart
52      outputBarChart();
53   } // end function processGrades
54
55   // find minimum grade
56   int GradeBook::getMinimum() const
57   {
58      int lowGrade = 100; // assume lowest grade is 100
59
60      // loop through grades array
61      for ( int grade : grades )
62      {
63         // if current grade lower than lowGrade, assign it to lowGrade
64         if ( grade < lowGrade )
65            lowGrade = grade; // new lowest grade
66      } // end for
67
68      return lowGrade; // return lowest grade
69   } // end function getMinimum
70
71   // find maximum grade
72   int GradeBook::getMaximum() const
73   {
74      int highGrade = 0; // assume highest grade is 0
75
76      // loop through grades array
77      for ( int grade : grades )
78      {
79         // if current grade higher than highGrade, assign it to highGrade
80         if ( grade > highGrade )
81            highGrade = grade; // new highest grade
82      } // end for
83
84      return highGrade; // return highest grade
85   } // end function getMaximum
86
87   // determine average grade for test
88   double GradeBook::getAverage() const
89   {
90      int total = 0; // initialize total
91
92      // sum grades in array
93      for ( int grade : grades )
94         total += grade;
95
96      // return average of grades
97      return static_cast< double >( total ) / grades.size();
98   } // end function getAverage
99
100  // output bar chart displaying grade distribution
101  void GradeBook::outputBarChart() const
102  {
103     cout << " Grade distribution:" << endl;
104
105     // stores frequency of grades in each range of 10 grades
106     const size_t frequencySize = 11;
107     array< unsigned int, frequencySize > frequency = {}; // init to 0s
108
109     // for each grade, increment the appropriate frequency
110     for ( int grade : grades )
111        ++frequency[ grade / 10 ];
112
113     // for each grade frequency, print bar in chart
114     for ( size_t count = 0; count < frequencySize; ++count )
115     {
116        // output bar labels ("0-9:", ..., "90-99:", "100:" )
117        if ( 0 == count )
118           cout << "  0-9: ";
119        else if ( 10 == count )
120           cout << "  100: ";
121        else
122           cout << count * 10 << "-" << ( count * 10 ) + 9 << ": ";
123
124        // print bar of asterisks
125        for ( unsigned int stars = 0; stars < frequency[ count ]; ++stars )
126           cout << '*';
127
128        cout << endl; // start a new line of output
129     } // end outer for
130  } // end function outputBarChart
131
132  // output the contents of the grades array
133  void GradeBook::outputGrades() const
134  {
135     cout << " The grades are: ";
136
137     // output each student's grade
138     for ( size_t student = 0; student < grades.size(); ++student )
139        cout << "Student " << setw( 2 ) << student + 1 << ": " << setw( 3 )
140           << grades[ student ] << endl;
141  } // end function outputGrades