Thread: contructors of Class memebers that are classes

When is the contructor called for a class thats been declared as a member of another class if you dont implicitly call the contructor? Is it called at all?

Try it out, this didn't take two minutes to type in:

Code:

class Member
{
public:
    Member() { cout << "Member class constructor called." << endl; };
};

class Base
{
public:
    Member m_Member;
    Base() { cout << "Base class constructor called." << endl; };
};

int main()
{
    Base MyBase;
    return 0;
}

This prints out the following on my system:
Member class constructor called.
Base class constructor called.

Looks like the Member class gets constructed first. Think about it a little. If the constructor for the Base class did stuff to the m_Member variable, itself a class, and that m_Member wasn't constructed yet, what would happen? So, the construction of any objects belonging to a class has to occur before the class itself.

>now take it easy again from the begining. u call that
>constructers but i dont see any constructers in your code!
That code relies on the default constructors that do not need to be defined, they're supplied by the compiler for the simple duty of creating objects. For further functionality you would need to define a specialized constructor.

-Prelude

That was my problem...stupidity. I was wondering about it, because I know you can explicity call the constructor...so I was thinking, why would it call it for you if sometimes you had to call it? And the answer, as you guys have awesomely pointed out, is that it only calls the default constructor, and you need to call explicitly if you want another constructor called. Braine freeze on my part...StonedCoder left his mark on me. Anyway, am I right to awesome that call a constructor supresses the default constructor from being called?