Creating a container class - Access violation

[Marein]

Hello there,

This being my first time on this forum, I hope my post is somewhat fitting to the rules and etiquette. I've only started learning C++ around two weeks ago so this might be a very basic question...

I'm trying to create a container class (ObjectArray) that holds an array of instances of another class (Object). I've boiled my problem down to the following code.

object.h

class Object
{
};

objectarray.h

#include "object.h"

class ObjectArray
{
private:
	int m_nLength;
	Object *m_pData;
public:
	void Initialise(int nLength);
};

objectarray.cpp

#include "objectarray.h"

void ObjectArray::Initialise(int nLength)
{
	m_pData = new Object[nLength];
	m_nLength = nLength;
}

main.cpp

#include "objectarray.h"

void main()
{
	ObjectArray *Objects;
	Objects = 0;
	Objects->Initialise(2);
}

The 2 in Objects->Initialise(2); is just an arbitrary number for testing purposes.

When I run this, I receive the following error:

Unhandled exception at 0x0041142e in Testing.exe: 0xC0000005: Access violation writing location 0x00000004.

Choosing Break brings me to line 5 in objectarray.cpp:
m_pData = new Object[nLength];

Mousing over m_pData gives me no tooltip (whereas nLength gives me '2' as expected).

I tried having a constructor for ObjectArray that set m_pData to 0, but that makes no difference. Inserting a new line into the Initialise function where m_pData is set to 0, produces the same error on that new line.

What is going wrong here? Thanks in advance!

[quirkyusername]

The problem isn't with your ObjectArray class you just havent allocated any memory for Objects in main, it's a null pointer when you try to call Initialise on it

[Marein]

Aah, so the solution is adding the following to main.cpp:

Objects = new ObjectArray;

Not it's working... Though I need to get my head around using pointers a bit more!

Thank you, quirky.