Abstract class:
When you want the class that doesn't create an object,than that class is declared with the modifier abstract,which contains non abstract method or abstract method(only structure is defined) and we have to implement in derived class.
Example:In Console Application
namespace Demo
{
class Demo:Operations
{
public static void Main(string []args)
{
Demo obj=new Demo();
obj.ReadOperations();
obj.add(4,5);
}
public override void add(int h,int g)
{
int c=h+g;
Console.WriteLine(c);
}
}
abstract class Operations
{
public abstract void add(int j,int k);
public void ReadOperations()
{
Console.WriteLine("Start Reading Operations:");
}
}
Output:
Start Reading Operations,
9.
Very Imp note:sealed,private,static,virtual(because implicity abstract is virtual),modifiers are not used while abstract keyword is used in class or in abstract methods.