We've now seen three different standard containers with the member functions push_back() and pop_back() (and, although we didn't mention it, back() to retrieve a reference to the last element of the container). These are the operations we'd need if we wanted to implement a stack data structure.
The standard library provides a convenient way to abstract the idea of a stack, with the container known as (what else?) std::stack. Unlike the containers we've seen so far, though, std::stack takes an extra template parameter.
std::stack<T, Ctr> represents a stack of elements of type T, where the underlying storage is managed by an instance of the container type Ctr. For example, stack<T, vector<T>> uses a vector to manage its elements; stack<T, list<T>> uses a list; and so on...
