What Is Inheritance?
¦ Goal: For reusability of code.
¦ Use inheritance to create new classes from existing ones.
¦ Between to 2 classes not 2 objects.
¦ Is a relationship
Example: Manger is an employee (Manger extends from Employee)
¦ Has a relationship: it means that class takes an object from another class.
¦ For example, the Bitmap class inherits from the Image class and extends it by adding functionality.
¦ General Shape to inheritance: Class Super: Sub { //do Something }
¦ You can easily create a custom exception class by inheriting from System.ApplicationException, as shown here:
class DerivedException : System.ApplicationException
{
public override string Message
{
get { return "An error occurred in the application."; }
}
}
// C# (In Main Class)
try
{
throw new DerivedException();
}
catch (DerivedException ex)
{
Console.WriteLine("Source: {0}, Error: {1}", ex.Source, ex.Message);
}
Output:
Source: UserExceptions, Error: An error occurred in the application.
We can display result in file by add this code:
catch (DerivedException ex)
{
// Console.WriteLine("Source: {0}, Error: {1}", ex.Source, ex.Message);
StreamWriter sw = new StreamWriter(@"location\fileName");
sw.WriteLine("Source: {0}, Error: {1}", ex.Source, ex.Message);
sw.Close( );
}
What Is an Interface?
ü Interfaces, also known as contracts (عقود اى يجب الالتزام بما بها).
ü Define a common set of members that all classes that implement the interface must provide.
ü For example, the IComparable interface defines the Compare To method, which enables two instances of a class to be compared for equality.
ü For example, the IDisposable is an interface that provides a single method, Dispose, to enable assemblies that create an instance of your class to free up any resources the instance has consumed.
ü You can create your own interfaces, see the following example:
Þ You should note that interface is public by default.
Þ In the case of inheritance the interface used as the follow:
ૈ class Myclass:YourClass,ImyInterface { //do something}
interface IMessage
{
//Method: Send the message. Returns True is success, False otherwise.
bool Send( );
// The message to send.
string Message { get; set; }
// The Address to send to.
string Address { get; set; }
}
class EmailMessage : IMessage
{
public bool Send()
{
throw new Exception("The method or operation is not implemented.");
}
public string Message
{
get
{
throw new Exception("The method or operation is not implemented.");
}
set
{
throw new Exception("The method or operation is not implemented.");
}
}
public string Address
{
get
{
throw new Exception("The method or operation is not implemented.");
}
set
{
throw new Exception("The method or operation is not implemented.");
}
}
}
What Are Partial Classes?
¦ Partial classes are new in .NET 2.0.
¦ Partial classes allow you to split a class definition across multiple source files.
¦ The Windows Form class is an example of a built-in partial class.
¦ Now that code is hidden in a partial class named form.Designer.cs.
¦ Note: Partial classes aren’t part of the exam objectives
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