Abstract class

• Abstract classes are solely for inheritance
• We can not create object of abstract class
• Abstract can not be sealed or static
• Abstract methods can not be private
• Abstract methods can not have the body
• Abstract method can not have the modifier virtual (By default it is virtual)
• Access modifier of the abstract method should be same in both abstract and derived class
• Abstract member can not be static

Overview in short

Private (No)

Static (No)

Sealed (No)

Virtual (No, by default virtual)

abstract class c# example

abstract class clsSave
{
    abstract public void Save();
}
class DerivedClass: clsSave
{
    // Area method is required to avoid
    // a compile-time error.
    public override void save()
    {
        //write code to save
    }
    static void Main()
    {
        DerivedClass objD= new DerivedClass();
        Console.WriteLine("Performing Save operation", objD.save());
    }
}