C++ Access Specifiers

Access Specifiers

Access specifiers control how the members (attributes and methods) of a class can be accessed.

They help protect data and organize code so that only the right parts can be seen or changed.

Using Access Specifiers

The public keyword is an access specifier.

In the example below, the members are public - which means that they can be accessed and modified from outside the code:

Example

class MyClass {  // The class
  public:        // Access specifier

// class members goes here
};

However, what if we want members to be private and hidden from the outside world?

In C++, there are three access specifiers:

• public - members are accessible from outside the class
• private - members cannot be accessed (or viewed) from outside the class
• protected - members cannot be accessed from outside the class, however, they can be accessed in inherited classes. You will learn more about Inheritance later.

Private

Members declared as private cannot be accessed from outside the class.

In the following example, we demonstrate the differences between public and private members:

Example

class
MyClass {

public:    // Public access
specifier
    int x;   // Public attribute

private:   // Private access specifier

int y;   // Private attribute
};

int main() {
  MyClass
myObj;
  myObj.x = 25;  // Allowed (public)
  myObj.y = 50;  //
Not allowed (private)

return 0;
}

Note: It is possible to access private members of a class using a public method inside the same class. See the next chapter (Encapsulation) on how to do this. Tip: It is considered good practice to declare your class attributes as private (as often as you can). This will reduce the possibility of yourself (or others) to mess up the code. This is also the main ingredient of the Encapsulation concept, which you will learn more about in the next chapter.

Note: By default, all members of a class are private if you don't specify an access specifier:

Example

class
MyClass {
  int x;   // Private attribute
  int y;   // Private attribute
};

Protected

Members declared as protected cannot be accessed from outside the class, but they can be accessed in child classes.

You will learn more about Inheritance in a later chapter.

Real-Life Example

• Public: Like the front door of your house - anyone can come in.
• Private: Like a locked drawer - only the owner (or trusted friends) can open it.
• Protected: Like a family-only room - children (subclasses) can enter, others cannot.