Very basic OOP question

SFORavi

I have a simple Employee Class as follows: I want to create a new Employee object from a different Class having Main Can I return the Complete Employee object from here when Main class uses GetEmployee method. The code below errors out saying variable e in last method below is undefined

namespace TestEmployee
{
class Employee
{

    int eId;
    string eName;
    double age;

    public Employee(int i, string n, double a)
    {
        eId = i;
        eName = n;
        age = a;
    }

    public Employee()
    {
        eId = 1105;
        eName = "Peter Cava";
        age = 32 ;
    }

    public Employee GetEmployee()
    {
        Employee e;


        e.eId = this.eId;
        e.eName = this.eName;
        e.eId = this.eId;

        return e;
    }

}

}

PIEBALDconsult

Employee e **= new Employee()**; (Though I don't know why you're cloning the Employee.)

Michael Handschuh

If you want to create a new employee from your main method you should just use:

Employee myEmployee = new Employee();

if you really want to have a cloned object you should have a look at the Interface ICloneable for implementing the right methods.

SFORavi

thanks for the reply I did create a new Employee Object

class Employee
{

    int eId;
    string eName;
    double age;

    public Employee(int i, string n, double a)
    {
        eId = i;
        eName = n;
        age = a;
    }

    public Employee()
    {

    }

    public Employee GetEmployee()
    {
        Employee e = new Employee();

        e.eId = this.eId;
        e.eName = this.eName;
        e.age = this.age;

        return e;
    }

}

and calling this from a form where I give the 3 inputs and want to see it in new set of fields

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

    private void button1\_Click(object sender, EventArgs e)
    {


        int i1 = Convert.ToInt32(textBox1.Text);
        string nm = textBox2.Text;
        double d2 = Convert.ToDouble(textBox3.Text);

        Employee em = new Employee(i1, nm, d2);

        em.GetEmployee();

      // Iam stuck on how to get the individual fields and display in separate box below.

        textBox5.Text = em.GetEmployee??  for Employee id from em object
        textBox6.Text = em.GetEmployee??  for Employee name from em object
        textBox6.Text = em.GetEmployee??  for Employee age from em object 





    }

Michael Handschuh

Well the problem is that all your variables in the employee class don't have public, or private set. In that case they will be private and only be seen within the class Employee. To manage that the correct way, C# offers you the posibility to create so called "Properties". I've created properties as you see in the code of the class.

public class Employee
{

// This is another example of writing properties
/*
private int eId;
private string eName;
private double age;

    public int EId
    {
       get{return eId;}
       set{eId = value;}
    }

    public string EName
    {
       get{return eName;}
       set{eName= value;}
    }

    public int Age
    {
       get{return age;}
       set{age= value;}
    }

*/
// Properties
public int EId{get;set;}
public string EName{get;set;}
public double Age{get;set;

    public Employee(int i, string n, double a)
    {
        eId = i;
        eName = n;
        age = a;
    }

    public Employee()
    {

    }

}

In the Form1 class you can access the properties pretty simple by creating a new Employee with Employee em = new Employee(); and access each property like: em.Name

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

    private void button1\_Click(object sender, EventArgs e)
    {


        int i1 = Convert.ToInt32(textBox1.Text);
        string nm = textBox2.Text;
        double d2 = Convert.ToDouble(textBox3.Text);

        Employee em = new Employee(i1, nm, d2);


      // Iam stuck on how to get the individual fields and display in separate box below.

        textBox5.Text = em.EId.ToString();
        textBox6.Text = em.EName;
        textBox6.Text = em.Age.ToString();
    }

Hope this helps.

SFORavi

Oh My, cant believe I dropped the ball on private and public declaration. Thanks very much for the details and how to use the properties. One last question please in the Employee class, if I have to return as an object I need to have a variable of the class and do a new, right like in

Employee e = new Employee();

in code below.

class Employee
{

    public int eId;
    public string eName;
    public double age;

    public Employee(int i, string n, double a)
    {
        eId = i;
        eName = n;
        age = a;
    }

    public Employee()
    {

    }

    public Employee GetEmployee()
    {
        Employee e = new Employee();

        e.eId = this.eId;
        e.eName = this.eName;
        e.eId = this.eId;

        return e;
    }

Not Active

You should not expose the class variables as public. Rather good design uses property accessors. That way any logic that may need to be executed when a property is set or accessed will be executed. You don't always need an instance of a class to access it's properties or methods.

public class Employee
{
private static int m_Id;

public static Foo()
{

}

public static int Id{get; set;}
}

int id = Employee.Id;
Employee.Foo();

Static methods and properties are not bound to an instance of a class. The Factory pattern quite often uses this to create instances

public class Employee
{
public static Employee CreateEmployee()
{
return new Employee();
}
}

Employee e = Employee.CreateEmployee();

No comment

BobJanova

I don't understand what the purpose of GetEmployee is. It is functionally doing a clone but that seems to be unnecessary.

arya1685

Hi, Just creating an Instance of Employee Class...... :laugh:

Thanks & Regards Arya1685 P Before printing think about your responsibility & commitment with the Environment! ü

SFORavi

Thanks very much Mark and Bob for the response. I think I am slowly getting it. Thanks, Ravi