Can We Execute a Parent Class Method If It Is Overridden in the Child Class?

Short Answer: Yes, you can execute a parent class method even if it is overridden in the child class. In C#, this is achieved using the base keyword, which allows you to call the parent class's method from within the overridden method in the child class.

Detailed Explanation:

In object-oriented programming, method overriding allows a child class (derived class) to provide a new implementation for a method that is already defined in its parent class (base class). When you override a method, the child class's version of the method is executed instead of the parent class's version. However, there are scenarios where you might want to execute the parent class's method alongside or within the child class's overridden method. This is where the base keyword comes into play.

How the base Keyword Works:

The base keyword in C# is used to access members (methods, properties, fields, etc.) of the base class from within the derived class. When you override a method in the child class, you can still call the parent class's version of the method using base.MethodName().

Example in C#:

Here’s an example to demonstrate how you can call a parent class method from an overridden method in the child class:

using System;

// Parent class
class Parent
{
    public virtual void SomeMethod()
    {
        Console.WriteLine("Parent class method");
    }
}

// Child class inheriting from Parent
class Child : Parent
{
    public override void SomeMethod()
    {
        Console.WriteLine("Child class method");

        // Call the parent class method using the base keyword
        base.SomeMethod();
    }
}

// Main program
class Program
{
    static void Main(string[] args)
    {
        Parent parent = new Parent();
        Child child = new Child();

        // Call the method on the Parent class instance
        parent.SomeMethod(); // Output: Parent class method

        // Call the method on the Child class instance
        child.SomeMethod();  // Output: Child class method
                              //         Parent class method
    }
}

Explanation of the Code:

1. Parent Class:
   • The Parent class defines a method named SomeMethod and marks it as virtual. This allows the method to be overridden in any derived class.
2. Child Class:
   • The Child class inherits from the Parent class and overrides the SomeMethod method using the override keyword.
   • Inside the overridden method, the child class first prints "Child class method".
   • It then calls the parent class's SomeMethod using base.SomeMethod(), which prints "Parent class method".
3. Main Method:
   • An instance of the Parent class is created, and SomeMethod is called. This executes the parent class's version of the method.
   • An instance of the Child class is created, and SomeMethod is called. This executes the child class's overridden method, which includes a call to the parent class's method.

Output:

When you run the above code, the output will be:

Parent class method
Child class method
Parent class method

Key Points to Remember:

1. Method Overriding: When a method in the parent class is marked as virtual, it can be overridden in the child class using the override keyword.
2. Using the base Keyword: The base keyword allows you to call the parent class's method from within the overridden method in the child class.
3. Execution Flow: When you call an overridden method on a child class instance, the child class's version of the method is executed. If the child class uses base.MethodName(), the parent class's version is also executed.
4. Practical Use Case: This approach is useful when you want to extend or modify the behavior of a parent class method in the child class while still retaining the original functionality of the parent class method.

Why This Matters:

Understanding how to use the base keyword to call parent class methods is essential for writing flexible and reusable code in object-oriented programming. It allows you to build on existing functionality without completely replacing it, making your code more modular and easier to maintain.

By following this approach, you can ensure that your derived classes are properly leveraging the behavior of their base classes while adding their own unique features.