Csharp/C Sharp/Class Interface/Class Deriving

Demonstrates deriving a new class from a base class in another assembly

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa
Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
//
//  Access1.cs - demonstrates deriving a new class from a base class in
//               another assembly. Also demonstrates how a derived class
//               may provide a public property to expose a protected member
//               of a base class.
//
//               Compile this program with the following command line:
//                   C:>csc /r:access.exe Access1.cs
//
namespace nsAccess
{
    using System;
    
    public class Access1
    {
        static public void Main ()
        {
            clsDerived derived = new clsDerived ();
            derived.AccessIt = 42;
            derived.ShowField ();
        }
    }
//
// Derive a class from the base class and give it a public
// property to access the private field in the base class
    class clsDerived : clsBase
    {
        public int AccessIt
        {
            get {return (Private);}
            set {Private = value;}
        }
    }
    public class clsBase
    {
        private int m_Private;
        protected int Private
        {
            get {return (m_Private);}
            set {m_Private = value;}
        }
        public void ShowField ()
        {
            Console.WriteLine ("The value of private field m_Private is " + m_Private);
        }
    }
    
}

the overridden methods of the System.Object class

 
using System;
using System.Collections;

public class Starter {
    public static void Main() {
        Employee obj1 = new Employee(5678);
        Employee obj2 = new Employee(5678);
        if (obj1 == obj2) {
            Console.WriteLine("equals");
        } else {
            Console.WriteLine("not equals");
        }
    }
}
class Employee {
    public Employee(int id) {
        if ((id < 1000) || (id > 9999)) {
            throw new Exception(
                "Invalid Employee ID");
        }
        propID = id;
    }
    public static bool operator ==(Employee obj1, Employee obj2) {
        return obj1.Equals(obj2);
    }
    public static bool operator !=(Employee obj1, Employee obj2) {
        return !obj1.Equals(obj2);
    }
    public override bool Equals(object obj) {
        Employee _obj = obj as Employee;
        if (obj == null) {
            return false;
        }
        return this.GetHashCode() == _obj.GetHashCode();
    }
    public override int GetHashCode() {
        return EmplID;
    }
    public string FullName {
        get {
            return propFirst + " " +
                propLast;
        }
    }
    private string propFirst;
    public string First {
        get {
            return propFirst;
        }
        set {
            propFirst = value;
        }
    }
    private string propLast;
    public string Last {
        get {
            return propLast;
        }
        set {
            propLast = value;
        }
    }
    private readonly int propID;
    public int EmplID {
        get {
            return propID;
        }
    }
    public override string ToString() {
        return FullName;
    }
}