Which access specifier is usually used for data members of a class?a) Protectedb) Privatec) Publicd) Default

Breakdown of the Problem

1. We need to identify the most commonly used access specifier for data members within a class.

Relevant Concepts

1. Access specifiers in object-oriented programming define the accessibility of class members (attributes and methods).
   • Private: Members are accessible only within the same class.
   • Protected: Members are accessible within the same class and subclasses.
   • Public: Members are accessible from outside the class.
   • Default: Members that do not have an explicit access specifier are accessible within the same package (in languages like Java).

Analysis and Detail

1. In encapsulation, which is a key principle of object-oriented programming, data members (attributes) are often set to private to restrict direct access from outside the class. This ensures that the internal representation of the object can be hidden and protected from unauthorized access and modifications.
2. Protected members are less common for data members since they allow derived classes to access them, which can lead to less control over the data.
3. Public members are usually reserved for methods that need to be accessible for manipulation of data rather than the data itself.
4. Default access specifier is specific to certain programming languages and is not the standard practice for data encapsulation.

Verify and Summarize

1. The best practice in class design is to declare data members as private and provide public getter and setter methods to access and modify them. This helps in maintaining control over the values being set to the data members.

Final Answer

b) Private is usually used for data members of a class to uphold encapsulation principles.