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C++ access specifiers

Control access and determine the scope of class members.

Three main type:

• private: best for attributes
• public: best for methods
• protected: like private but allows inherited classes to access those members

Declare with private: or public:

class Sport {
private:
    int number = 1;
public:
    std::string running;
};

Private keyword

By default, class members are private. They cannot be directly access from outside the class.

Note: declare class attributes as private whenever possible.

Public keyword

public members are accessible anywhere in the program.

It is best used for methods. Provide ways for the program to interact with an instance of the class.

Encapsulation

Encapsulation in OOP programming means hiding details about an object’s implementation.

In C++ this translate by declaring a class members/attributes as private. So they cannot be accessed from outside the class.

However, if the program may need to interact with those values, it can still do so with accessor functions and mutator functions (getter and setter).

Accessor functions

An accessor functions (or getter) is a public function that return the value of a private member.

class Clock {
private:
    int time = 1200;
    
public:
    // getter for time
    int getTime() {
        return time;
    }
};

Note: Accessor functions should always have a return type that matches the type of the member it is accessing.

Mutator function

A mutator function (or setter) is a public function that sets the value of a private member.

class Clock {
private:
    int time = 1200;
    
public:
    // setter for time
    void setTime(int new_time) {
        time = new_time;
    }
};

Note: They usually have a void return type and one parameter of the same type as the attribute.