Access violation writing?

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C++

class Student {
public:
	//Accessor
	int fetchAge();
	int *fetchDaysInCourse();
	string fetchEmail();
	string fetchFirstName();
	string fetchLastName();
	string fetchStudentId();
	Degree fetchDegreeType();
	//Mutators
	void mutateAge(int);
	void mutateDaysInCourse(int[1]);
	void mutateEmail(string);
	void mutateFirstName(string);
	void mutateLastName(string);
	void mutateStudentId(string);
	void mutateDegreeType(Degree);
	
	//other handlers
	virtual void print();
	virtual Degree fetchDegreeProgram();
	//constructor
	Student(int age, int daysInCourse[3], string studentId, string email, string firstName, string lastName, Degree degreeType);
	~Student();

private:
	int Age, DaysInCourse[1];
	string Email, FirstName, LastName, StudentId;
	Degree DegreeType;

};

C++

using namespace std;

int main() {

	//personal information for start screen
	cout << "Course Title: Scripting and Programming - Applications - C867 \n";
	cout << "Language used: C++ \n";
	cout << "Student ID: 467185 \n";
	cout << "Written by: Gregory Young \n\n";

	Roster classRoster;

	const string studentData[] =
	{
		"A1,John,Smith,John1989@gm ail.com,20,30,35,40,SECURITY",
 "A2,Suzan,Erickson,Erickson_1990@gmailcom,19,50,30,40,NETWORK",
 "A3,Jack,Napoli,The_lawyer99yahoo.com,19,20,40,33,SOFTWARE",
 "A4,Erin,Black,Erin.black@comcast.net,22,50,58,40,SECURITY",
 "A5,Gregory,young,gyoun15@wgu.edu,29,30,20,33,40,SOFTWARE"
	};

	//fill the class roster array
	for (int i = 0; i < sizeof(studentData) / sizeof(studentData[i]); i++) {
		cout << studentData[i] << endl;
		string input = studentData[i];
		istringstream ss(input);
		string token;
		string tempHolder[9];

		int x = 0;
		while (x < 9 && getline(ss, token, ',')) {
			tempHolder[x] = token;
			x += 1;
		}

		Degree studentDegree;
		if (tempHolder[8] == "NETWORK") {
			studentDegree = NETWORKING;
		}
		else if (tempHolder[8] == "SECURITY") {
			studentDegree = SECURITY;
		}
		else if (tempHolder[8] == "SOFTWARE") {
			studentDegree = SOFTWARE;
		}
		else {
			studentDegree = NODEGREE;
		}

		classRoster.add(tempHolder[0], tempHolder[1], tempHolder[2], tempHolder[3], std::stoi(tempHolder[4]), std::stoi(tempHolder[5]), std::stoi(tempHolder[6]), std::stoi(tempHolder[7]), studentDegree);
	}

	classRoster.printAll();
	cout << "\n";
	classRoster.printInvalidEmails();
	cout << "\n";
	for (int i = 0; i < sizeof(classRoster.classRosterArray) / sizeof(classRoster.classRosterArray[i]); i++) {
		classRoster.printDaysInCourse(classRoster.classRosterArray[i]->fetchStudentId());
	}
	cout << "\n";
	classRoster.printByDegreeProgram(SOFTWARE);
	cout << "\n";
	classRoster.remove("A3");
	classRoster.remove("A3");

	return 0;
}

void Roster::add(string studentID, string firstName, string lastName, string email, int age, int daysInCourse1, int daysInCourse2, int daysInCourse3, Degree degreeProgram)
{
	int courseDays[3] = { daysInCourse1, daysInCourse2, daysInCourse3 };

	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		if (classRosterArray[i] == nullptr) {
			if (degreeProgram == NETWORKING) {
				classRosterArray[i] = new NetworkStudent(age, courseDays, studentID, email, firstName, lastName, degreeProgram);
			}
			else if (degreeProgram == SECURITY) {
				classRosterArray[i] = new SecurityStudent(age, courseDays, studentID, email, firstName, lastName, degreeProgram);
			}
			else if (degreeProgram == SOFTWARE) {
				classRosterArray[i] = new SoftwareStudent(age, courseDays, studentID, email, firstName, lastName, degreeProgram);
			}
			else {
				classRosterArray[i] = new Student(age, courseDays, studentID, email, firstName, lastName, degreeProgram);
			}

			break;//stop 
		}
	}
}

void Roster::printAll()
{
	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		classRosterArray[i]->print();
	}
}

void Roster::printByDegreeProgram(int degreeProgram)
{
	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		if (classRosterArray[i]->fetchDegreeProgram() == degreeProgram) {
			classRosterArray[i]->print();
		}
	}
}

void Roster::printDaysInCourse(string studentID)
{
	float avg = 0;
	int max = 3;
	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		if (classRosterArray[i] != nullptr && classRosterArray[i]->fetchStudentId() == studentID) {
			int *daysInCourse = classRosterArray[i]->fetchDaysInCourse();
			for (int x = 0; x < max; x++) {
				avg += daysInCourse[x];
			}

			cout << "Student " << classRosterArray[i]->fetchStudentId() << "'s average number of days in each course is." << (avg / max) << "\n";
			break;
		}
	}
}

void Roster::printInvalidEmails()
{
	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		string email = classRosterArray[i]->fetchEmail();
		bool isValid = false;

		size_t found = email.find("@");
		if (found != string::npos) {
			found = email.find(".");
			if (found != string::npos) {
				found = email.find(" ");
				if (found == string::npos) {
					isValid = true;
				}
			}
		}

		if (!isValid) {
			cout << email << " is not a valid email address \n";
		}
	}
}

void Roster::remove(string studentID)
{
	bool studentRemoved = false;
	for (int i = 0; i < sizeof(classRosterArray) / sizeof(classRosterArray[i]); i++) {
		if (classRosterArray[i] != nullptr && classRosterArray[i]->fetchStudentId() == studentID) {
			classRosterArray[i] = nullptr;
			studentRemoved = true;
			break;
		}
	}

	if (studentRemoved == false) {
		cout << "ERROR: Student ID '" << studentID << "' was not found.";
	}
}

Roster::~Roster()
{
	delete * classRosterArray;
}
string Student::fetchEmail()
{
	return Email;
}

#include "Student.h"

//basic operation for return of requested information 

int Student::fetchAge()
{
	return Age;
}

int * Student::fetchDaysInCourse()
{
	return DaysInCourse;
}

void Student::mutateEmail(string email)
{
	Email = email;
}

string Student::fetchEmail()
{
	return Email;
}

string Student::fetchFirstName()
{
	return FirstName;
}

string Student::fetchLastName()
{
	return LastName;
}

string Student::fetchStudentId()
{
	return StudentId;
}

Degree Student::fetchDegreeType()
{
	return Degree();
}

void Student::mutateAge(int age)
{
	Age = age;
}


void Student::mutateDaysInCourse(int *daysInCourse)
{
	for (int i = 0; i < 3; i++) {
		DaysInCourse[i] = daysInCourse[i];
	}
}


void Student::mutateFirstName(string firstName)
{
	FirstName = firstName;
}

void Student::mutateLastName(string lastName)
{
	LastName = lastName;
}

void Student::mutateStudentId(string studentId)
{
	StudentId = studentId;
}

void Student::mutateDegreeType(Degree degreeType)
{
	DegreeType = degreeType;
}

Student::Student(int age, int daysInCourse[3], string studentId, string Email, string firstName, string lastName, Degree degreeType)
{
 mutateAge(age);
mutateStudentId(studentId);
mutateEmail(Email);
mutateFirstName(firstName);
mutateLastName(lastName);
mutateDegreeType(degreeType);
mutateDaysInCourse(daysInCourse);
mutateDegreeType(degreeType);
}

void Student::print()
{
	int *daysInCourse = fetchDaysInCourse();

	cout << fetchStudentId() << "\t";
	cout << "First Name: " << fetchFirstName() << "\t";
	cout << "Last Name: " << fetchLastName() << "\t";

	cout << "Age: " << fetchAge() << "\t";
	cout << "daysInCourse: " << daysInCourse[0] << "8" << daysInCourse[1] << "8" << daysInCourse[2] << "\t";

	cout << "Degree Program: ";
	switch (fetchDegreeProgram()) {
	case 0: cout << "Security";
		break;
	case 1: cout << "Networking";
		break;
	case 2: cout << "Software";
		break;
	case 4: cout << "Unknown or Unspecified";
		break;
	}
	
}

Degree Student::fetchDegreeProgram()
{
	return NODEGREE;
}

Student::~Student()
{
}

What I have tried:

I am getting a read access violation on the line Return Email; I have included the associated code from Student class as well. I am not really sure why it is running into a read access violation Email is apparently unable to read the characters from the string.

Posted 8-Nov-18 7:04am

gtyoung2

Updated 9-Nov-18 6:21am

v7

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Comments

John R. Shaw 8-Nov-18 13:26pm

Try "while (x < 9 && getline(ss, token, ','))" to start with.

gtyoung2 8-Nov-18 14:21pm

That resolved that issue thank you! unfortunately, I have run into another error now reading for my fetch email function. It apparently has an issue reading the string, I have added this to the question above if you are willing to take a look

Richard MacCutchan 8-Nov-18 15:56pm

Please edit your question with the updated code and explain exactly what the problem is and where it occurs.

gtyoung2 8-Nov-18 16:12pm

done.

Richard MacCutchan 8-Nov-18 16:22pm

Yes but you have not explained anything. We cannot guess what Email refers to.

gtyoung2 8-Nov-18 16:28pm

Email should ultimately refer to the email string specified in
//constructor
Student(int age, int daysInCourse[3], string studentId, string email, string firstName, string lastName, Degree degreeType);
which is an email address that gets assigned to the array via
const string studentData[] =
{
"A1,John,Smith,John1989@gm ail.com,20,30,35,40,SECURITY",
"A2,Suzan,Erickson,Erickson_1990@gmailcom,19,50,30,40,NETWORK",
"A3,Jack,Napoli,The_lawyer99yahoo.com,19,20,40,33,SOFTWARE",
"A4,Erin,Black,Erin.black@comcast.net,22,50,58,40,SECURITY",
"A5,Gregory,young,gyoun15@wgu.edu,29,30,20,33,40,SOFTWARE"
};
and the class roster array

Richard MacCutchan 9-Nov-18 4:18am

But it doesn't. If you actually go through the above code you do not assign anything to Email.

Richard MacCutchan 9-Nov-18 4:19am

"Email should ultimately refer to"
That's all well and good, but what does it actually refer to? I cannot find anywhere in the above code where you assign any value to that variable.

gtyoung2 9-Nov-18 11:46am

It should be assigned in the void Student::mutateEmail(string email). Sorry I did not include this section previously. I am pretty bad at this, thank you for your time.

Richard MacCutchan 9-Nov-18 11:48am

Saying "it should be ..." does not really help. You need to use the debugger to trace exactly what is happening, as we cannot run all that code, or guess what happens.

gtyoung2 9-Nov-18 11:57am

Problem is the Debug is not really taking me to where the problem is happening.
'Project1.exe' (Win32): Loaded 'C:\Users\greg\source\repos\Project1\Debug\Project1.exe'. Symbols loaded.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ntdll.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel32.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\KernelBase.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Program Files\AVAST Software\Avast\aswhookx.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp140d.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\vcruntime140d.dll'. Cannot find or open the PDB file.
'Project1.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ucrtbased.dll'. Cannot find or open the PDB file.
Exception thrown at 0x56504BB7 (vcruntime140d.dll) in Project1.exe: 0xC0000005: Access violation reading location 0x00000028.

Then takes me to the line string Student::fetchEmail()
{
return Email; <-
}

Which says error reading characters of the string. Is there a way I can dig a bit deeper into the debugger to trace what you need?

Richard MacCutchan 9-Nov-18 13:08pm

You need to look at the stack trace to see how it reached that point from your program. The trace should give you method names and/or source line numbers. You could also add breakpoints at the locations where that variable is being accessed. Unfortunately this sort of error is never easy to find, you just need to keep trying different things.

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KarstenK · Answer 1 · 2018-11-09T06:21:00

Solution 1

You need to use the debugger for solving that problem. Typical for your last problem is that the Student object is invalid like a null pointer or deallocated memory.

Set a break point some calls before that crash.

Posted 9-Nov-18 6:21am

KarstenK