Class Object Error 'Undefined Reference For'

Question

I get the following error when calling the class object and functions in a class instance:

1) fig7_17.cpp:

fig07_17.cpp

#include <array>
#include "GradeBook.h" 
using namespace std;

// function main begins program execution
int main()
{
   
   const array< int, GradeBook::students > grades = 
      { 87, 68, 94, 100, 83, 78, 85, 91, 76, 87 }; 
   string courseName = "CS101 Introduction to C++ Programming";

   GradeBook myGradeBook( courseName, grades );
   myGradeBook.displayMessage();
   myGradeBook.processGrades(); 
} 

2) Gradebook.cpp :

// Fig. 7.16: GradeBook.cpp

#include <iostream>
#include <iomanip>
#include "GradeBook.h" 
using namespace std;

GradeBook::GradeBook( const string &name, 
   const array< int, students > &gradesArray )
   : courseName( name ), grades( gradesArray )
{
} 

void GradeBook::setCourseName( const string &name )
{
   courseName = name; 
} 


string GradeBook::getCourseName() const
{
   return courseName;
} 
void GradeBook::displayMessage() const
{
   cout<< "Welcome to the grade book for\n" << getCourseName() << "!" 
      << endl;
} 

void GradeBook::processGrades() const
{
   // output grades array
   outputGrades();

   // call function getAverage to calculate the average grade
   cout << setprecision( 2 ) << fixed; 
   cout << "\nClass average is " << getAverage() << endl;

   // call functions getMinimum and getMaximum
   cout << "Lowest grade is " << getMinimum() << "\nHighest grade is "
      << getMaximum() << endl;

   // call function outputBarChart to print grade distribution chart
   outputBarChart();
} // end function processGrades

int GradeBook::getMinimum() const
{
   int lowGrade = 100; // assume lowest grade is 100

   // loop through grades array
   for ( int grade : grades )
   {
      // if current grade lower than lowGrade, assign it to lowGrade
      if ( grade < lowGrade )
         lowGrade = grade; // new lowest grade
   } // end for

   return lowGrade; // return lowest grade
} // end function getMinimum


int GradeBook::getMaximum() const
{
   int highGrade = 0; // assume highest grade is 0

   // loop through grades array
   for ( int grade : grades )
   {
      // if current grade higher than highGrade, assign it to highGrade
      if ( grade > highGrade )
         highGrade = grade; // new highest grade
   } // end for

   return highGrade; // return highest grade
} // end function getMaximum     

// determine average grade for test
double GradeBook::getAverage() const
{
   int total = 0; // initialize total

   // sum grades in array
   for ( int grade : grades )
      total += grade;

   // return average of grades
   return static_cast< double >( total ) / grades.size();
} // end function getAverage


void GradeBook::outputBarChart() const
{
   cout << "\nGrade distribution:" << endl;

   // stores frequency of grades in each range of 10 grades
   const size_t frequencySize = 11;
   array< unsigned int, frequencySize > frequency = {}; // init to 0s

   // for each grade, increment the appropriate frequency
   for ( int grade : grades )
      ++frequency[ grade / 10 ];

   
   for ( size_t count = 0; count < frequencySize; ++count ) 
   {
      // output bar labels ("0-9:", ..., "90-99:", "100:" )
      if ( 0 == count )
         cout << "  0-9: ";
      else if ( 10 == count )
         cout << "  100: ";
      else
         cout << count * 10 << "-" << ( count * 10 ) + 9 << ": ";
      
      // print bar of asterisks
      for ( unsigned int stars = 0; stars < frequency[ count ]; ++stars )
         cout << '*';

      cout << endl; // start a new line of output
   } 
} 


void GradeBook::outputGrades() const
{
   cout << "\nThe grades are:\n\n";

   // output each student's grade
   for ( size_t student = 0; student < grades.size(); ++student )
      cout << "Student " << setw( 2 ) << student + 1 << ": " << setw( 3 )
         << grades[ student ] << endl;
} 

3) GradeBook.h:

#include <string> 
#include <array>

class GradeBook
{
public:
   // constant -- number of students who took the test
   static const size_t students = 10; // note public data

   // constructor initializes course name and array of grades
   GradeBook( const std::string &, const std::array< int, students > & );

   void setCourseName( const std::string & ); 
   std::string getCourseName() const; 
   void displayMessage() const;
   void processGrades() const; 
   int getMinimum() const;  
   int getMaximum() const; 
   double getAverage() const; 
   void outputBarChart() const;
   void outputGrades() const; 
private:
   std::string courseName; 
   std::array< int, students > grades; 
}; 

Error:

C:\Users\PC\AppData\Local\Temp\cciKxoUd.o:fig07_17.cpp:(.text+0xa5): undefined reference to `GradeBook::GradeBook(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::array<int, 10u> const&)'
C:\Users\PC\AppData\Local\Temp\cciKxoUd.o:fig07_17.cpp:(.text+0xb5): undefined reference to `GradeBook::displayMessage() const'
C:\Users\PC\AppData\Local\Temp\cciKxoUd.o:fig07_17.cpp:(.text+0xc2): undefined reference to `GradeBook::processGrades() const'
collect2.exe: error: ld returned 1 exit status
[Finished in 330ms]

   

I may have used wrong terms because I did not understand some situations. But I fixed it. I'm sorry. I think the written code is correct. I use sublime text by the way.

I tried to access the class members and functions but I got a error.(how to program C++ - Exeample 7_15_17)