C++ Tutorial – class

A class in C++ is an encapsulation of data members and functions that manipulate the data. The class can also have some other important members which are architecturally important. 
   This C++ Tutorial discusses the components of a C++ class. More C++ tutorials will follow.

C++ Tutorial – Class Data Members:

Very important point about the Data members in this C++ Tutorial! This title is not a keyword or a data type in C++. This is just to explain one of the logical classifications of the types of members that are available in C++.
The data members can be of any legal data type, a class type, a struct type etc., They can also be declared as pointers and accessible normally as like other data members. The Example class given below in this C++ tutorial has two data members x and y of type integer.

C++ Tutorial – Function members in classes:

Functions declared inside a class can be any of the following four types. This C++ Tutorial explains each one of them as below.

Ordinary member functions :

These are ordinary functions defined with a return type and parameters. The return type can also be void. The special trait about member functions is they can access the private/protected data members of their class and manipulate them. No external functions can access the private/protected data members of a class. The sample below this C++ Tutorial uses an ordinary member function Add(), returning an integer value.


Constructors in C++ are special member functions of a class. They have the same name as the Class Name. There can be any number of overloaded constructors inside a class, provided they have a different set of parameters. There are some important qualities for a constructor to be noted.

  • Constructors have the same name as the class.
  • Constructors do not return any values
  • Constructors are invoked first when a class is initialized. Any initializations for the class members, memory allocations are done at the constructor.

In the example class given below in this C++ tutorial has the constructor Example_Class(), with the same name as the class.


Destructors in C++ also have the same name, except for the fact that they are preceded by a ‘~’ operator. The destructors are called when the object of a class goes out of scope. It is not necessary to declare a constructor or a destructor inside a class. If not declared, the compiler will automatically create a default one for each. If the constructor/destructor is declared as private, then the class cannot be instantiated. Check below for the sample class of the C++ tutorial for an example of destructor.

C++ Tutorial – Access Level:

The classes in C++ have 3 important access levels. They are Private, Public and Protected. The explanations are as follows.


The members are accessible only by the member functions or friend functions.


These members are accessible by the member functions of the class and the classes which are derived from this class.


Accessible by any external member. Look at the sample class below.

C++ Tutorial – Example of a class:

class Example_class //Sample Class for the C++ Tutorial
int x; //Data member
int y; // Data member
Example_Class() //Constructor for the C++ tutorial
x = 0;
y = 0;
~Example_Class() //destructor for the C++ Tutorial
{ }
int Add()
return x+y;