Question

I have three files.

file 1
This has the class definition and all the methods in the class are also defined here

file 2
The object of the above class is instantiated here

file 3
Here I want to call one of the methods using the object created in file 2

I am trying to do above thing is because I want the code to be modular. Is there a better way to do this? Can you post any other solution that you may have?

Answer 1

Put your definition into an header file (usually .h):

//header File1.h
class File1
{
    void Foo();
};

Include definition and implement it in another file (usualy .cpp)

//File1.cpp
#include "File1.h"

File1::Foo()
{

}

Then include the header with the definitions where you want to use

//File2.cpp

#include "File1.h"

File1 file1;
file1.Foo();

Remember that the 2 translation units must be linked together.