what is the meaning of data hiding

Question

One of the most important aspects of OOP is data hiding. Can somebody explain using a simple piece of code what data hiding is exactly and why we need it?

Answer 1

Data Hiding is defined as hiding a base class method in a derived class by naming the new class method the same name as the base class method.

class Person
{
  public string AnswerGreeting()
  {
     return "Hi, I'm doing well. And you?";
  }
}

class Employee : Person
{
   new public string AnswerGreeting()
   {
      "Hi, and welcome to our resort.";
   }
}

In this c# code, the new keyword prevents the compiler from giving a warning that the base class implementation of AnswerGreeting is being hidden by the implementation of a method with the same name in the derived class. Also known as "data hiding by inheritance".