An Abstract class is a special class which is majorly used for inheritance and it cannot be instantiated.
• Cannot be instantiated i.e. object cannot be created using the new keyword.
• Can contain both Abstract and Non-Abstract members.
• Abstract members are simply declared and are defined in the classes deriving the Abstract class.
• Abstract members are defined by using the override keyword.
• Non-Abstract members are defined within the Abstract class.
• Non-Abstract members can be accessed within the derived classes only if marked public or protected.
• Private Non-Abstract members are not accessible outside the Abstract class.
• Abstract and Non-Abstract members can be accessed using the derived classes.
• Does not support Multiple Inheritance.
Example:public abstract class A
{
public abstract void Fun1();
public void Fun4()
{
}
protected void Fun5()
{
}
private void Fun6()
{
}
}
public class B : A
{
public override void Fun1()
{
}
public void Fun2()
{
//Valid
Fun4();
Fun5();
//Compiler Error: Cannot create an instance of the abstract class or interface
Fun6();
}
}
public class C
{
public static void Fun3()
{
//Compiler Error: Cannot create an instance of the abstract class or interface 'A'
A a = new A(); //Valid
B b = new B();
b.Fun1();
b.Fun2(); b.Fun4();
}
}
