5.15 C++ How to Program (8th Edition) By Paul Deitel, Harvey Deitel

(GradeBook Modification) Modify the GradeBook program  5.11 to calculate the grade-point average. A grade of A is worth 4 points, B is worth 3 points, and so on.
Solution: 

 #include <string>
using std::string;
 
//GradeBook class definition
class GradeBook
{
public:  
  GradeBook( string ); // course name initialization with constructor
  void setCourseName( string ); // course name set function
  string getCourseName(); //course name get function
  void displayMessage(); //display greeting message
  void inputGrades(); //enter random grade count
  void displayGradeReport(); // display entered grades report
private:
  string courseName;
  int aCount;
  int bCount;
  int cCount;
  int dCount;
  int fCount;
};
 
 #include "GradeBook.h"

 
int main()
{
 
  GradeBook myGradeBook( "CS101 C++ Programming" );
 
  myGradeBook.displayMessage();
  myGradeBook.inputGrades();
  myGradeBook.displayGradeReport();
 
   //for pause
   system("PAUSE");
   return 0;
}
 

#include <iostream>
using std::cout;
using std::cin;
using std::endl;
 
#include "GradeBook.h"
 
 
//constructor
GradeBook::GradeBook( string name )
{
  setCourseName( name );
  aCount = 0;
  bCount = 0;
  cCount = 0;
  dCount = 0;
  fCount = 0;   
}
 
// course name limit
void GradeBook::setCourseName( string name )
{
  if( name.length() <= 25 )
    courseName = name;
  else
  {
     courseName = name.substr( 0, 25);
     cout << "Name \"" << name << "\" exceeds maximum length (25).\n"
       << "LImiting courseName to first 25 characters.\n" << endl;
   }
}
 
//function get course name
string GradeBook::getCourseName()
{
  return courseName;
}
 
//function display message
void GradeBook::displayMessage()
{
 
 
  cout << "Welcome to the grade book for\n"
    << getCourseName() << "!\n" << endl;
}
 
//input random count of grades
void GradeBook::inputGrades()
{
  int grade;
 
  cout << "Enter the letter grades."
    << "Enter th EOF character to end input." << endl;
 
 
  while ( ( grade = cin.get() ) != EOF )
   {
 
      switch( grade )
      {
        case 'A':
        case 'a':
          aCount++;
          break;
        case 'B':
        case 'b':
          bCount++;
          break;
        case 'C':
        case 'c':
          cCount++;
          break;
        case 'D':
        case 'd':
          dCount++;
          break;
        case 'F':
        case 'f':
          fCount++;
          break;
        case '\n':
        case '\t':
        case ' ':
          break;
        default:
          cout << "Incorrect letter grade entered."
              << " Enter a new grade." << endl;
      }
    }
}     
//report    
void GradeBook::displayGradeReport()
{
  cout << "\n\nNumber of students who received each letter grade:"
    << "\nA: " << aCount
    << "\nB: " << bCount
    << "\nC: " << cCount      
    << "\nD: " << dCount
    << "\nF: " << fCount
      << endl;
 
   cout << "Average point is " 
     << (aCount * 4 + bCount * 3 + cCount * 2 + dCount * 1 + fCount * 0)/(aCount + bCount + cCount + dCount + fCount) << endl;       
}