what is mean by *adj and how it is working

Question

I started working with the C++ STL and I am learnimg about list.

I know that in list<int> adj, adj is an object of list class in which int are stored.

My doubt is, what is mean by *adj in list<int> *adj;?

Answer 1

This declares adj to be a pointer to a list<int>:

list<int> *adj;

It does not construct a list<int> but can be used to point at list<int>s constructed elsewhere in the program. Example:

list<int> a_list_int_instance;

adj = &a_list_int_instance; // & is the "address-of" operator in this context

adj now points at a_list_int_instance and can access its methods by dereferencing. Here are two options:

adj->push_back(10);
(*adj).push_back(20);