Thread: Class inheritance

Does this statement make sense in regards to the following program? Be gentle

(Derived class employee)’s header takes an argument to (base class person) which gives it access to (base class person)’s properties.

Code:

#include <string>
#include <iostream>

using namespace std;

class Person
{
protected:
	string firstName;
	string lastName;

public:
	Person(void)
	{
		cout << "In the Person constructor (a derived class)" << endl;
		cout << "Enter a first name: ";
		cin >> firstName;
		cout << "Enter a last name: ";
		cin >> lastName;
	}

	string getFirstName(void)
	{
		return firstName;
	}

	string getLastName(void)
	{
		return lastName;
    }
};

class Employee : public Person
{
protected:
	float salary;

public:
	Employee()
    {
		cout << "In the Employee constructor (a derived class)" << endl;
		cout << "Enter a salary (no commas): ";
		cin >> salary;
    }
	
	float getSalary(void)
    {
        return salary;
	}
};


int main (void)
{
	Employee Number_one; // calls constructor of Person, then constructor of Employee
	Employee Number_two; // calls constructor of Person, then constructor of Employee
	
	cout << endl << endl << endl;
	
	cout << "Retrieving Number_one's first name and last name from class Person:\n";
	cout << "   "<< Number_one.getFirstName() << " " << Number_one.getLastName() << endl;
	cout << "\nRetrieving Number_one's salary from class Employee:\n";
    cout << "   " << Number_one.getSalary() << endl;

	cout << endl << endl << endl;

	cout << "Retrieving Number_two's first name and last name from class Person:\n";
	cout << "   " << Number_two.getFirstName() << " " << Number_two.getLastName() << endl;
	cout << "\nRetrieving Number_two's salary from class Employee:\n";
    cout << "   " << Number_two.getSalary() << endl;

	system("PAUSE");
	return 0;
}

(Derived class employee)’s header takes an argument to (base class person) which gives it access to (base class person)’s properties.

"Header" is not meaningful, and "properties" is incomplete as well as unconventional terminology. How about "Employee is a more specialized form of Person"?

A few criticisms of your code.

Code:

string getFirstName(void)

This isn't C. In C++, if you have a function that takes no arguments, it's just string getFirstName() without the void.

Also, try to learn const-correctness early on. For instance, your getFirstName-method is a simple getter. You could make the method const, promising that invoking that method on an instance of your Person class will not change any of the data members of the class (which is always a sensible promise for getter methods).

Code:

string getFirstName() const // <-- note the const

Lastly, it is generally not a good idea to make data members protected. It's better to keep them private and provide protected accessor methods via which derived classes can modify those data members if needed.