Question

I know this as this will assign the constructor parameter to the class member:

class A
{
    public:
        some_type B;
        A(some_type B)
        {
            this->B = B;
        }
}

But what will this do:

class A
{
    public:
        some_type B;
        A(some_type B) : B(B)
        {
        }
}

Will this assign the parameter to itself or the parameter to the class member or do something else?
How are the names in the list after construct thing (I have no idea how its called) resolved?

Answer 1

Will this assign the parameter to itself or the parameter to the class
member or do something else?

It will assign the parameter to the class member.

How are the names in the list after construct thing (I have no idea
how its called) resolved?

This is the initializers list, and though the example can lead to confusion, the id at the left of the parenthesis is a member of the class, while the id (or literal) inside the parenthesis can only be one of the parameters of the constructor: thought that way, there is no ambiguity at all.

The key here is that this list must initialize class members with some value, so if you think of

...: B(B)

as conceptually equivalent to a constructor call:

this->B(B)

… there is no ambiguity.