C++ Access Specifiers
Access Specifiers
By now, you are quite familiar with the public keyword that appears in all of our class examples:
Example
class MyClass { // The class
public: // Access specifier
// class members goes here
};
Run example »
The public keyword is an access specifier.
Access specifiers define how the members (attributes and methods) of a class can
be accessed. In the example above, the members are public - which means that they
can be accessed and modified from outside the code.
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 classprivate- members cannot be accessed (or viewed) from outside the classprotected- members cannot be accessed from outside the class, however, they can be accessed in inherited classes. You will learn more about Inheritance later.
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;
}
If you try to access a private member, an error occurs:
error: y is private
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
};
