C++ Primer, Fifth Edition

Defining an Adaptor

Each adaptor defines two constructors: the default constructor that creates an empty object, and a constructor that takes a container and initializes the adaptor by copying the given container. For example, assuming that deq is a deque<int>, we can use deq to initialize a new stack as follows:

stack<int> stk(deq);  // copies elements from deq into stk

By default both stack and queue are implemented in terms of deque, and a priority_queue is implemented on a vector. We can override the default container type by naming a sequential container as a second type argument when we create the adaptor:

// empty stack implemented on top of vectorstack<string, vector<string>> str_stk;// str_stk2 is implemented on top of vector and initially ...