passing a reference of an object through constructor

Question

I have a class CM which has a constructor as follow:

CM::CM(const std::vector<Something>& vector1, const SomethingElse&     something):myVector(vector1),mySomething(something)
{
}

and from another class (class Ad) I want to create an object

Ad.h

CM* cmObj;

Ad.cpp

Ad::Ad()
{
cmObj = (CM*) malloc(1);
}

and I also want to instantiate my cmObj to NULL. How can I do that?

Answer 1

Pre C++11, use cmdObj = NULL to set the pointer to a null pointer value.

Don't use malloc and cast, as the constructor to CM will not be called and things like virtual function tables will not be set up correctly.

Use cmObj = new CM(/*ToDo - constructor arguments here*/); instead. Don't forget to call delete cmObj; somewhere (the destructor for Ad is a good place).