Object Oriented Design

Question

Hi,

I need to write a course class & student class and run them using a driver.

I've written my codes, and the program runs fine, however, i want to enrol 3 students into my course but it doesn't seem to work. The program only manages to check the 1st student, but not the 2nd and 3rd student. I have no idea what is wrong with my program.

I hope someone could help me with this problem.

heres my codes

Course.cpp

#include <iostream>
#include <vector>
#include <string>
#include "Course.h"
using namespace std;
//Constructor
Course::Course()
{
}
Course::Course(string a)
{
    CourseName=a;
}
//destructor
Course::~Course()
{
}
//checks student enrolled with ID
bool Course::isEnrolled(string StudentID)
{
    for (int i=0; i<students.size(); i++)
        {
                if (students[i].getStudentID() == StudentID)
                {
                        return true;
                }
                else
                {
                        return false;
                }
        }
}
//stores student in vector
void Course::enrolStudents(Student student)
{
    students.push_back(student);
}



Course.h

#include <iostream>
#include <string>
#include <vector>
#include "Student.h"
#ifndef COURSE_H
#define COURSE_H
class Course
{
    public:
    // constructor
    Course();
    Course(std::string a);
    // destructor
    ~Course();
    //declaration of private methods
    bool isEnrolled(std::string StudentID);
    void enrolStudents(Student student);
    private:
    std::string CourseName;     //Course Name
    std::vector<Student> students;   //vector to store students
}; 
#endif  // end of class definition



Student.cpp

#include <iostream>
#include <string>
#include "Student.h"
using namespace std;
// constructor for your class
Student::Student()
{
}
Student::Student(string newID, string newName)
{
        ID = newID;
        Name = newName;
}
// destructor for your class
Student::~Student()
{
}
//Accessor Functions
string Student::getStudentID()
{
        return ID;
}
string Student::getStudentName()
{
        return Name;
}
//Sets the student name attribute data/Mutator
void Student::setStudentName(string newName)
{
        Name = newName;
}
//Sets the student ID attribute data/Mutator
void Student::setStudentID(string newID)
{
        ID = newID;
}
//displays the output
void Student::display()
{
        cout << "Name: "<< Name << endl;
        cout << "ID: " << ID << endl;
}



Student.h

#include <iostream>
#include <string>
using namespace std;
#ifndef STUDENT_H
#define STUDENT_H
class Student
{
    public:
    // constructor
    Student();
    Student(string, string);
    // destructor
    ~Student();
    //Accessors
    string getStudentName();
    string getStudentID();
    //declaration of private methods
    void setStudentName(string newName);
    void setStudentID(string newID);
    void display();
    private:
    string ID;  //Student ID
    string Name;    //Student Name
}; 
#endif



driver.cpp

#include "Student.h"
#include "Course.h"
int main()
{
        Student student;
        student.setStudentID("123");
        student.setStudentName("abc");
        student.display();
        Course course;
        Student a("Tom" , "1");
        course.enrolStudents(a);
        cout<<course.isEnrolled("Tom");
        Student b("Jas" , "2");
        course.enrolStudents(b);
        cout<<course.isEnrolled("Jas");
        course.enrolStudents(Student("Kio" , "3"));
        cout<<course.isEnrolled("Kio");
        cout << "check" << endl;
        string check;
        cin >> check;
        if(course.isEnrolled(check))
        cout << "Students Enrolled" << endl;
        Else
        cout << "Students not Enrolled" << endl;
        return 0;
}

Answer 1

You return immediatly:

bool Course::isEnrolled(string StudentID)
{
    for (int i=0; i<students.size(); i++)
        {
                if (students[i].getStudentID() == StudentID)
                {
                        return true;
                }
                else
                {
                        return false;
                }
        }
}

This should be:

bool Course::isEnrolled(string StudentID)
{
    for (int i=0; i<students.size(); i++)
        {
                if (students[i].getStudentID() == StudentID)
                {
                        return true;
                }
        }

    return false;
}

Answer 2

I also remark an issue with your include guards. Please your header includes in your include guards, eg:

#ifndef _NAMESPACE_FILE_H_
#define _NAMESPACE_FILE_H_
#pragma once //for the compilers that support it (VS does)

#include <blah>
...

#endif //_NAMESPACE_FILE_H_

Answer 3

thanks, that solved my problem.

however, i'm trying to create a driver that read an input.txt file instead of manually typing each student into the driver.

I'm unable to get the driver to read off any data from the input.txt, i hope some1 could help me out with this

heres my input.txt and my driver.cpp

Tom 123
Jas 456
Kio 789

#include<iostream>
#include<fstream>
#include<string>
#include "Course.h"
#include "Student.h"

using namespace std;

int main(){

Course course;
string Name,temp; string ID; 
	ifstream myfilestream;
	myfilestream.open("input.txt");
	if (myfilestream.fail())
	{
		cout<<"filestream open failed\n";
		return -1;
	}
			
	do
	{
		myfilestream>>temp;
		myfilestream>>Name;
		Name+=temp;
		myfilestream>>ID;
		course.enrolStudents(Student(Name,ID));
				
	}
	while(myfilestream.good());
	myfilestream.close();
	cout<<"Enter to check if student is enrolled\n";
	string check;
	cin>>check;
	if(course.isEnrolled(check))
		cout<<"Student " << check << "is currently enrolled" << endl;
	else
		cout<<"Student not enrolled" << endl;

	return 0;
}

Answer 4

You should read these references:
http://www.cplusplus.com/reference/iostream/ifstream/
http://www.cplusplus.com/reference/iostream/istream/operator%3E%3E/

This is standard ISO C++, and there is a learning curve to it...

Answer 5

I've read those references, however i still do not understand why my driver.cpp doesn't read the input.txt file to enrol the students into the course

could you further elobrate more on it?

Answer 6

The first thing to note is that you're not testing
for failure of the input stream in the right place.
The fundamental rule is: Always test after every I/O
request is attempted to see if it failed, and do so
*before* trying to use any data that may have been
retrieved from an input operation.

You are doing stream extractions (>>) and *assuming*
that they will always succeed by trying to use the
data before checking to see if a failure occurred.

You also are not checking at the end to see whether
file reading ended due to eof having been reached
or because of a read error.

You have two fields per student in the file,
but you are extracting three strings from the
file each iteration.

Tom 123
Jas 456
Kio 789

do {
   myfilestream>>temp; // What is this for?
   myfilestream>>Name;
   Name+=temp;
   myfilestream>>ID;
...

- Wayne