I previously mentioned in Basics of Object Oriented Programming that the main body of any class that we write in our program is usually written in a separate file called .cpp file and its declarations in another header file .h file. This is done in order to avoid clustering of the class definition with the execution body of the program. It makes it pretty easy and efficient to put all the classes in separate files in a large program. This is then included later in a main file and its functions are used in the manner we like. Here is the detailed procedure for it.