How to call class object in main that is declared in header?

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Hello ppl. How to call my class object indirect from my object.h header file in to main.cpp file, because i don't want to declare my class object in main.cpp? Which pointer type is need to use better?
For example:

// object.h
MyClass MyObject(1);
int * pMyObject;
pMyObject = &MyObject;

// class.cpp
#include "class.h"
#include "object.h"
MyClass::MyClass
{
...
}

// class.h
Class MyClass
{
...
};

// main.cpp
#include <iostream>
#include "class.h"
#include "object.h"
int main()
{
MyClass MyObject(1); // I need somehow to point my declaration from header,
// but do not declare in main.cpp
MyObject->setFunc(); MyObject->getFunc();
}
</iostream>

Is it possible? Any ideas? Thanks for help.

Posted 30-Mar-11 7:46am

MNMR

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-03-30T08:17:00

It looks like you badly misuse header files. Also, you mess up unrelated concepts: separate compilation, access of instances and memory allocation.

It is very bad idea to put any objects in a header file. Put only types and method declarations (and some inline definitions, see below). Just thing of how include works and you will understand why.

This is a usual pattern:

MyClass.h:

C++

class MyClass {
public:
	MyClass(int value) : m_Value(value) { }
	int Value() const { return m_Value; }
	int SomeSeriousMethod();
private:
	int m_Value;
};

MyClass.cpp:

C++

#pragma once
#include <stdafx.h> //only if you use pre-compiled headers
#include "MyClass.h"

int MyClass::SomeSeriousMethod() { /*...*/ }

Usage:

C++

#include "MyClass.h"

//..

void SomeFunction() {
	MyClass instanceOnStack(1);
	int value1 = instanceOnStack.SomeSeriousMethod();
	MyClass * instanceInHeap = new MyClass(2);
	int value2 = instanceInHeap->SomeSeriousMethod();
        //...
        //you can access existing stack instance by pointer as well:
	MyClass * someOtherInstance = &instanceOnStack;
	value2 = someOtherInstance->SomeSeriousMethod();
        //...
	//important; better do it under try-finally; this is a "finally" part:
        delete instanceInHeap;
}

—SA