c++ - Is the constructor of a class called if you declare a object of that class as an instance variable of another class?

Question

For example, if i have a class like this;

#import "B.h"
class A
{
    B object;
};

would B's constructor get called when I created a A object?

Answer 1

Yes, the default constructor will be called (if present) or a compiler error will be triggered if there is no default constructor for B.

Answer 2

Yes. One way to test this is to put some simple cout calls in the constructors to watch the constructor calls happen.

Answer 3

Yes, member constructor is called in order of declaration for the containing class.

Answer 4

One should mention that this rule apply both ways, calling class 'A's destructor calls its members default destructor's.