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Abstraction and Polymorphism, question.

v8n3t (17)
Hello everyone,

I am working on a project for school and had a general question. I researched the error I am getting upon compilation and found out the reason for the error.

I want this to be at the top of my post in case my instructor finds this post online! I am not asking for an answer or asking anyone to write my program for me. I am asking for clarification and giving an example of the code I am using and hoping for clarity on this topic. The rest of the project is easy "smiley face here".

I am however unsure on the solution. I am working a bit ahead of myself so please do not pay too much attention to my driver. I was just working on creating iterators and also my vector of employee objects.

I found this: "Any class with one or more pure virtual functions is an abstract class, and it is illegal to instantiate an object of it. Trying to do so will cause a compile-time error. Putting a virtual function in your class signals two things to clients of your class:
*Don't make an object of this class, derive from it.
*Make sure you override the pure virtual function."

source: http://www.cplusplus.com/forum/general/4153/

So I am still unsure on how to correct it to fix this issue.

I am asking for clarification on how to correctly work around Abstraction with Polymorphism.

Please keep in mind my code is not complete and I am still working on it.

Employee.h
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#include <iostream>
#include <string>

using std::string;

class Employee
{
protected:

	int intEmpId;
	double dblEmpPay;
	string strEmpId;
	string strEmpName;
	string strEmpStatus;


public:

	Employee();
	~Employee();

	virtual void setEmpId(int id) = 0;
	virtual void setEmpName(string name) = 0;
	virtual void setEmpPay(double pay) = 0;
	virtual void setEmpStatus(char a, char b) = 0;


};

class PartTime: public Employee
{
private:

public:

	PartTime()
	{

	}

	~PartTime();

	void setEmpId(int id)
	{

	}

	void setEmpName(string name)
	{

	}

	void setEmpPay(double pay)
	{

	}

	void setEmpStatus(char a, char b)
	{

	}

};

class FullTime: public Employee
{
private:

public:

	FullTime()
	{

	}

	~FullTime();

	void setEmpId(int id)
	{

	}

	void setEmpName(string name)
	{

	}

	void setEmpPay(double pay)
	{

	}

	void setEmpStatus(char a, char b)
	{

	}
};

class Contractor: public Employee
{
private:

public:

	Contractor()
	{

	}

	~Contractor();

	void setEmpId(int id)
	{

	}

	void setEmpName(string name)
	{

	}

	void setEmpPay(double pay)
	{

	}

	void setEmpStatus(char a, char b)
	{

	}
};

driver.cpp
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#include <iostream>
#include <iomanip>
#include <fstream>
#include <string>
#include <vector>
#include "Employee.h"

using namespace std;

void main()
{
	vector<Employee> vEmp;

	vector<Employee>::const_iterator iBegin = vEmp.begin();
	vector<Employee>::const_iterator iBegin = vEmp.end();

	fstream fstObj;
	string temp = "";
	
	fstObj.open("employees.dat", fstream::in | fstream::out | fstream::app);

	while(fstObj.good())
	{

		getline(fstObj, temp);

		//(int)temp.find('|');
	}
	

}


cbeginplusplus (7)
I would say from this:
 
 
virtual void setEmpId(int id) = 0;


you have to decide if its
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virtual void setEmpId() = 0;
// or 
virtual void setEmpId(int id) {}

v8n3t (17)
cbeginplusplus,

Thank you for your response. After looking at your answer I looked into this subject even further. I read the entire document here: http://www.cplusplus.com/doc/tutorial/polymorphism/

I found out that I would have ran into an issue later on trying to instantiate an object from an Abstract class. I also found the workaround to that is to just create a pointer to it instead :P

Now I have a question which I can not answer by reading online.

I was under the impression that by including the signature of my functions like such
 
 
virtual void setEmpId(int id) = 0;


that this means "Ok compiler, I am creating the signature for this function in the parent class but LOOK AT MY Child class's for the actual function to be used."

I thought this was how we used Abstraction with Polymorphic behavior.

I also understand that by appending the = 0 to the end of the function I am making that virtual function abstract.

Now without the abstraction applied, is polymorphism still used?
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