Need some clarification on Scoping in the Private Section of a Class

[leo255]

I'm going through Paul Deitel's C++ fundamentals video course, and encountered a small scoping issue. Below is my GradeBook Class code. I left out the main cpp, as all it really does is initialize a grades array with 10 numbers, and calls the processGrades function in the class below.

I usually like to put my private variables section of a class first, so I can see them easily, but when I did that, I got a lot of scoping errors (i.e. "Grade not declared in scopre," "Numbers not declared in scope," etc.). Took me a while to figure out that placing private under public got rid of those scoping issues, and I just want to know why, so I can understand what I did wrong.

Thanks.

#ifndef GRADEBOOK_H
#define GRADEBOOK_H

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

class GradeBook{

public:

    const static int students = 10;
    GradeBook( string name, const int gradesArray[]){
    setCourseName( name );
    for ( int grade = 0; grade < students; grade++ )
    grades[ grade ] = gradesArray[ grade ];
}

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

    void processGrades(){

    outputGrades();

    cout << "\nClass average is " << setprecision(2) << fixed << getAverage() << endl;
    cout << "Lowest grade is " << getMinimum() << "\nHighest grade is " << getMaximum() << endl << endl;
    outputBarChart();
    }

    int getMinimum(){

    int lowGrade = 100;

    for (int grade = 0; grade < students; grade++){
        if (grades[grade] < lowGrade)
        lowGrade = grades[grade];

    }
    return lowGrade;
    }

    int getMaximum(){

    int highGrade = 0;

    for ( int grade = 0; grade < students; grade++){
        if (grades[grade] > highGrade)
            highGrade = grades[grade];
    }
    return highGrade;
    }

    void outputGrades(){

    cout << "\nThe grades are:\n\n";

    for (int student = 0; student < students; student++)
        cout << "Student " << setw(2) << student + 1 << ": " << setw(3) << grades[student] << endl;
    }

void outputBarChart(){

const int frequencySize = 11;
int frequency[frequencySize] = {};
for (int grade = 0; grade < students; grade++)
    frequency[grades[grade]/10]++;

for (int count = 0; count < frequencySize; 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 < frequency[count]; stars++)
    cout << '*';
   cout << endl;;
}}

double getAverage(){

int total = 0;
for (int grade = 0; grade < students; grade++)

    total += grades[grade];
    return static_cast<double>(total)/students;
    }

    string getCourseName(){
    return courseName;
    }
    void displayMessage(){
    cout << "\nWelcome to the GradeBook for " << getCourseName() << "!" << endl;
    }

    private:

int grades[students];
string courseName = "";
};

#endif // GRADEBOOK_H

[LB]

I think the issue is that your indentation style makes it incredibly difficult to tell what's inside the class vs what's inside a function.

The order and number of public/private/protected indicators does not matter.

I used NetBeans to automatically reformat your code, this is how NetBeans arranged it:

#ifndef GRADEBOOK_H
#define GRADEBOOK_H

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

class GradeBook
{
public:

	const static int students = 10;

	GradeBook(string name, const int gradesArray[])
	{
		setCourseName(name);
		for(int grade = 0; grade < students; grade++)
			grades[ grade ] = gradesArray[ grade ];
	}

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

	void processGrades()
	{

		outputGrades();

		cout << "\nClass average is " << setprecision(2) << fixed << getAverage() << endl;
		cout << "Lowest grade is " << getMinimum() << "\nHighest grade is " << getMaximum() << endl << endl;
		outputBarChart();
	}

	int getMinimum()
	{

		int lowGrade = 100;

		for(int grade = 0; grade < students; grade++)
		{
			if(grades[grade] < lowGrade)
				lowGrade = grades[grade];

		}
		return lowGrade;
	}

	int getMaximum()
	{

		int highGrade = 0;

		for(int grade = 0; grade < students; grade++)
		{
			if(grades[grade] > highGrade)
				highGrade = grades[grade];
		}
		return highGrade;
	}

	void outputGrades()
	{

		cout << "\nThe grades are:\n\n";

		for(int student = 0; student < students; student++)
			cout << "Student " << setw(2) << student + 1 << ": " << setw(3) << grades[student] << endl;
	}

	void outputBarChart()
	{

		const int frequencySize = 11;
		int frequency[frequencySize] = {};
		for(int grade = 0; grade < students; grade++)
			frequency[grades[grade] / 10]++;

		for(int count = 0; count < frequencySize; 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 < frequency[count]; stars++)
				cout << '*';
			cout << endl;
			;
		}
	}

	double getAverage()
	{

		int total = 0;
		for(int grade = 0; grade < students; grade++)

			total += grades[grade];
		return static_cast<double>(total) / students;
	}

	string getCourseName()
	{
		return courseName;
	}

	void displayMessage()
	{
		cout << "\nWelcome to the GradeBook for " << getCourseName() << "!" << endl;
	}

private:

	int grades[students];
	string courseName = "";
};

#endif // GRADEBOOK_H 

[Stewbond]

I'm going to re-post this code because to read it, I had to re-format it. Indenting is incredibly important because otherwise you can't see your structures. I couldn't tell where one function started and the other ended:

This code was able to compile. Was this an example of the working or not working code? I see that your two members: grades[] and courseName are both private here.

class GradeBook
{
public:
    const static int students = 10;
    
    GradeBook( string name, const int gradesArray[])
    {
        setCourseName( name );
        for ( int grade = 0; grade < students; grade++ )
            grades[ grade ] = gradesArray[ grade ];
    }

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

    void processGrades()
    {
        outputGrades();

        cout << "\nClass average is " << setprecision(2) << fixed << getAverage() << endl;
        cout << "Lowest grade is " << getMinimum() << "\nHighest grade is " << getMaximum() << endl << endl;
        outputBarChart();
    }

    int getMinimum()
    {
        int lowGrade = 100;

        for (int grade = 0; grade < students; grade++)
        {
            if (grades[grade] < lowGrade)
                lowGrade = grades[grade];
        }
        return lowGrade;
    }

    int getMaximum()
    {
        int highGrade = 0;

        for ( int grade = 0; grade < students; grade++)
        {
            if (grades[grade] > highGrade)
                highGrade = grades[grade];
        }
        return highGrade;
    }

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

        for (int student = 0; student < students; student++)
            cout << "Student " << setw(2) << student + 1 << ": " << setw(3) << grades[student] << endl;
    }

    void outputBarChart()
    {
        const int frequencySize = 11;
        int frequency[frequencySize] = {};
        for (int grade = 0; grade < students; grade++)
            frequency[grades[grade]/10]++;

        for (int count = 0; count < frequencySize; 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 < frequency[count]; stars++)
                cout << '*';
            cout << endl;;
        }
    }

    double getAverage()
    {
        int total = 0;
        for (int grade = 0; grade < students; grade++)
            total += grades[grade];
            
        return static_cast<double>(total)/students;
    }

    string getCourseName()
    {
        return courseName;
    }
    void displayMessage()
    {
        cout << "\nWelcome to the GradeBook for " << getCourseName() << "!" << endl;
    }
    
private:
    int grades[students];
    string courseName = "";
};

[vlad from moscow]

It would be better if you will post error messages and the statements that are marked as errorneous.

[LB]

There are no error messages, he specifically stated that this is the code that compiled.

leo255 wrote:

Took me a while to figure out that placing private under public got rid of those scoping issues, and I just want to know why, so I can understand what I did wrong.

[vlad from moscow]

@L B

There are no error messages, he specifically stated that this is the code that compiled.

leo255 wrote:

Took me a while to figure out that placing private under public got rid of those scoping issues, and I just want to know why, so I can understand what I did wrong.

Does it mean that we shall guess what is the problem?

[vlad from moscow]

I think the problem is that when you exchange the public and private sections variable students becomes undefined for array grades. The order of data member declarations is important. So variable students shall be defined before grades[students]

[leo255]

Thanks for the help, guys!

I apologize for the messy code - I will make sure that further code is formatted more legibly in the future.