How to make function private in a class in C++

Here what I have: I have a project in visual studio with window forms.

file1 myClass.cpp

string myClass::myFunction(std::string text) { //function code return var; }

....

file 2 myClass.h

#pragma once #ifndef MYCLASS_H #define MYCLASS_H #include <string> #include <windows.h> using namespace std; class MyClass { private: string myFunction(string text); };

....

file 3 main.cpp

myClass myObject; string data = myObject.myFunction(string text);

....

I it doesn't work.