What is the purpose of the override keyword in C#?

In C#, the purpose of the override keyword is to allow subclasses to rewrite virtual methods, abstract methods, or implement methods defined in the base interface. By using the override keyword, subclasses can provide their own implementation logic, overriding methods defined in the base class or interface.

The conditions for using the “override” keyword:

1. Use the “override” keyword only in derived classes to override methods in a base class or interface.
2. The overridden method must be a virtual method marked with the ‘virtual’ keyword in the base class, an abstract method marked with the ‘abstract’ keyword in the base class, or a method defined in the base interface.
3. The overriding method must have the same signature as the method being overridden (method name, parameter types, return type).

Characteristics of rewriting methods:

1. The overridden methods in child classes must be marked with the “override” keyword to indicate that they are overriding methods from the parent class.
2. The access modifier of a overridden method can be different from the base class method, but it cannot be more restrictive.
3. The override method allows the child class to call the original implementation in the base class, using the base keyword to call the base class method.
4. The override method can add new functionality or completely replace the implementation of the base class method.
5. The overridden method can be further overridden or replaced by derived classes.

By using the override keyword, subclasses can modify or extend methods in the base class or interface according to their own requirements, achieving polymorphism and a flexible code structure.