Си++.Выходит ошибка E2235 Member function must be called or its address taken

void __fastcall TForm1::Button1Click(TObject *Sender)
{     int n1;  n1 = StrToInt( Edit1 -> Text );
  float y; array obx(n1);
      for(int i=0;i<n1;i++)  {StringGrid1->Cells[0][i]=IntToStr(obx[i]);}
 
        y=obx.M3;
 
    Edit2 -> Text = FloatToStr(y);
}

y=obx.M3();

//---------------------------------------------------------------------------
#include <vcl.h>
#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <string>
 
using namespace std;
 
class GradeBook
{
        public:
           const static int students=10;
           GradeBook(string,const int[]);
           void setCourseName(string);
           string getCourseName();
           void displayMessage();
           void processGrades();
           int getMinimum();
           int getMaximum();
           double getAverage();
           void outputBarChart();
           void outputGrades();
        private:
           string courseName();
           int grades[students];
};
//---------------------------------------------------------------------------
#include <vcl.h>
#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <string>
#include "Unit2.h"
 
using namespace std;
 
GradeBook::GradeBook(string name,const int gradesArray[])
{
        setCourseName(name);
        for(int grade=0;grade<students;grade++)
          grades[grade]=gradesArray[grade];
}
void GradeBook::setCourseName(string name)
{
        courseName=name;
}
string GradeBook::getCourseName()
{
        return courseName;
}
void GradeBook::displayMessage()
{
        cout << "Welcome to the grade book for\n" << getCourseName() <<"!"<<endl;
}
void GradeBook::processGrades()
{
        outputGrades();
 
        cout << "\nClass average is " << setprecision(2) << fixed <<
             getAverage() << endl;
        cout << "Lowest grade is: " << getMinimum()
             << "\nHighest grade is: " << getMaximum() << endl;
        outputBarChart();
}
int GradeBook::getMinimum()
{
        int lowGrade=100;
        for(int grade=0;grade<students;grade++)
        {
           if(grades[grade]<lowGrade)
             lowGrade=grades[grade];
        }
        return lowGrade;
}
int GradeBook::getMaximum()
{
        int highGrade=0;
        for(int grade=0;grade<students;grade++)
        {
           if(grades[grade]>highGrade)
              highGrade=grades[grade];
        }
        return highGrade;
}
double GradeBook::getAverage()
{
        int total=0;
        for(int grade=0;grade<students;grade++)
           total+=grades[grade];
        return static_cast<double>(total)/students;
}
void GradeBook::outputBarChart()
{
        cout << "\nGrade distribution: " <<endl;
        const int friquencySize=11;
        int friquency[friquencySize]={0};
        for(int grade=0;grade<students;grade++)
           friquency[grades[grade]/10]++;
        for(int count=0;count<friquencySize;count++)
        {
           if(count==0)
              cout << "  0-9: ";
           else if(count==10)
              cout << "  100: ";
           else
              cout << count*10 << "-" << (count*10)+9 << ": ";
           for(int stars=0;stars<friquencySize[count];stars++)
              cout << "*";
           cout <<endl;
        }
}
void GradeBook::outputGrades()
{
        cout << "\n The grades are:\n\n";
        for(int student=0;student<students;student++)
           cout << "Student " << setw(2) << student+1 << ": "
                << setw(3) << grades[student] <<endl;
}
//---------------------------------------------------------------------------
#include <vcl.h>
#include <iostream>
#include <cstdlib>
#include <iomanip>
#include <string>
#include "Unit2.h"
 
using namespace std;
 
int main()
{
        int gradeArray[GradeBook::students]={87,68,94,100,83,78,85,91,76,87};
        GradeBook myGradeBook("CS101 Introduction to C++ Programming",gradeArray);
        myGradeBook.displayMessage();
        myGradeBook.processGrades();
        cout <<endl;
        system("pause");
        return 0;
}

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