Question

Possible Duplicate:
Class construction with initial values

While I was looking at c++ example in http://en.wikipedia.org/wiki/Delegation_pattern I noticed something I haven’t seen before:

C() : i(new A()) { }

My question is: How is this line of code any different from:

C() {
    i = new A();
}

What does : after constructor do? What does the brackets around new A() do?

Answer 1

Its called initialization list. It is used to initialize the data members of a class.

C() {
    i = new A(); // i is not initialized here, here assignment is taking place.
}