Initializing private member variables of a class

Question

I apologize in advance because some of my verbiage may not be 100% correct.

I will have a class like this:

class ClassName {
private:
    AnotherCl         


        

Answer 1

AnotherClass class2; creates another local object inside the constructor body, that gets destroyed at the end of the body. That is not how class members are initialized.

Class members are initialized before the constructor body in the member initializer list between the constructor signature and body, starting with a :, like so:

ClassName::ClassName() :
    class2(argumentsToPassToClass2Constructor),
    anotherMember(42) // just for example
{
    /* constructor body, usually empty */
}

If you don't want to pass any arguments to the class2 constructor you don't have to put it in the initializer list. Then its default constructor will be called.

If you simply want to call the default constructor on all of your class members, you can (and should) omit the constructor altogether. The implicitly generated default constructor will do just what you wanted.