Help with functions and arrays

[bbalistic8]

Hi there I am currently trying to calculate an output based on an array passed into a function.

However I am stuck with how to pass the array into the function. I have the code written in the function to do what is required, however I cannot send in the information required to output. Please help. The c++ file inputs information from a file and is stored into multiple arrays. The code for the program is follows:

//An educational institution has a file that contains a list of student IDs, names and marks for
//eight subjects. The educational institution needs to know certain statistics based on this
//data.
#include <fstream>
#include <iomanip>
#include <string>
#include <iostream>
using namespace std;

class Student 
{
public:
	int studentID;
	string studentFirstName;
	string studentLastName;
	Student::Student(int,string,string);
	Student::Student(){};
	int getID(){return studentID;};
	string getFirstName(){return studentFirstName;};
	string getLastName(){return studentLastName;};
};
Student::Student(int inID, string inFirstName, string inLastName)
{
	Student newStudent[12];
	for (int i=0;i<12;i++)
	{
		newStudent[i].studentID=inID;
		newStudent[i].studentFirstName=inFirstName;
		newStudent[i].studentLastName=inLastName;
	}
}
class Grade : public Student
{
public:
	int grade[8];
	string subject;
	double stuAverage;
	double stuTotals;
	Grade::Grade(int);
	Grade::Grade(string);
	Grade::Grade(){};
	double getStudentAverage()
	{
		stuTotals = 0;
		for(int i=0;i<8;i++)
		{
			stuTotals = (stuTotals + grade[i]);
		}
		stuAverage = stuTotals/8;
		return stuAverage;
	};
	double getStudentTotal()
	{
		stuTotals = 0;
		for (int i=0;i<8;i++)
		{
			stuTotals = (stuTotals + grade[i]);
		}
		return stuTotals;
	};
	string getSubject()
	{
		return subject;
	};
	int getValue(int inGrade){return grade[inGrade];};
};
Grade::Grade(int inGrade)
{
	for(int i=0;i<8;i++)
	{
		grade[i]=inGrade;
	}
};
Grade::Grade(string inSubject)
{
		subject=inSubject;
};

class SubjectAverage : public Student
{
public:
	string subjectName;
	double countMarks;
	double totalMarks;
	void calculateAverageSubjects(Grade subjects[])
	{
		string name;
		double total=0;
		int matchedElements=0;
		SubjectAverage avgArray[12]; 
		bool found=false;
		for (int i=0;i<12;i++)                     //initialise array of SubjectAverages
		{
			avgArray[i].subjectName=="";          //
			avgArray[i].countMarks=0;
			avgArray[i].totalMarks=0;
		}
		for (int i=0;i<12;i++)                     //for each record in array
		{
			name=subjects[i].subject;            //get subject name from array
	    
			for (int j=0;j<8;j++)                   //for each if the grades
			{
				total=total+subjects[i].grade[j];  //get total of grades
			}
	        
			int index=0;                            //index is the index into the subject averages array
	        
			while(index <= matchedElements && ! found)               //search array of averages from beginning
			{
				if (avgArray[index].subjectName==name)          //if matched with the current object name, not new so add total and increment count
				{
					found=true;
					avgArray[index].countMarks=avgArray[index].countMarks+8;
					avgArray[index].totalMarks=avgArray[index].totalMarks+total;
				}
				index=index+1;
			}
			if (! found)                                //else write new record to array to the subject average Array
				{
					avgArray[matchedElements].subjectName=name;
					avgArray[matchedElements].totalMarks=total;
					avgArray[matchedElements].countMarks=8;
					matchedElements++;
				}
			total=0;
			found=false;
		}
		for (int j=0;j<matchedElements;j++)
		{
			cout<<avgArray[j].subjectName<<" "<<(avgArray[j].totalMarks/avgArray[j].countMarks)<<endl;
		}
	}
};

int main()
{
	Grade newStudent[12];
	Grade results[8];
	ofstream outFile("results.txt", ios::app); 
	ifstream inData ("grades.txt");

	if(!outFile) 
	{ 
		cout << "Cannot open export file.\n"; 
		return 1; 
	}
	if(!inData) 
	{ 
		cout << "Cannot open input file.\n";
		return 1;
	}
    
	int i=0;
	for (i=0;i<12;i++)
	{
		inData>>newStudent[i].studentID;
		inData>>newStudent[i].studentFirstName;
		inData>>newStudent[i].studentLastName;
		for (int k=0;k<8;k++)
		{
			inData>>newStudent[i].grade[k];
			Grade(newStudent[i].grade[k]);
		}
		inData>>newStudent[i].subject;
		Grade(newStudent[i].subject);	
		Student(newStudent[i].studentID, newStudent[i].studentFirstName, newStudent[i].studentLastName);	
	}
			
	cout<<fixed<<setprecision(2);
	for (int i=0;i<12;i++)
	{
		outFile<<newStudent[i].getID()<<" "<<newStudent[i].getFirstName()<<" "<<newStudent[i].getLastName()<<endl;
		outFile<<"	";
		for (int j=0;j<8;j++)
		{
			outFile<<newStudent[i].getValue(j)<< " ";
		}
			outFile<<"	Average Mark: "<<newStudent[i].getStudentAverage()<<endl;
	}
	for (int i=0;i<12;i++)
	{
		cout<<newStudent[i].getID()<<" "<<newStudent[i].getLastName()<<"		"<<newStudent[i].getSubject()<<"	"<<newStudent[i].getStudentAverage()<<endl;
	}
	
	cout<<"\n \n ------------ Average Mark per Subject ------------"<<endl;
	cout<<"Math:		"<<"??"<<endl;
	cout<<"Programming:	"<<"??"<<endl;
	cout<<"English:	"<<"??"<<endl;
	cout<<"Sport:		"<<"??"<<endl;
	cout<<"Drama:		"<<"??"<<endl;
	cout<<"Religion:	"<<"??"<<endl;
	cout<<"Science:	"<<"??"<<endl;

	cout<<"\n \n ------------ Number of Students per Subject ------------"<<endl;
	cout<<"Math:		"<<"??"<<endl;
	cout<<"Programming:	"<<"??"<<endl;
	cout<<"English:	"<<"??"<<endl;
	cout<<"Sport:		"<<"??"<<endl;
	cout<<"Drama:		"<<"??"<<endl;
	cout<<"Religion:	"<<"??"<<endl;
	cout<<"Science:	"<<"??"<<endl;

	cout<<"\n\nThe grand total average of all subjects: "<<"??"<<endl;

	calculateAverageSubjects(subject);
	return 0;
}

Where it is outputting the subject average = ?? is what will be replaced by the call to calculateAverageSubjects(array).

Can someone please tell me where I have gone wrong.