HP Integrity NonStop H-Series - Manual (Page 115)

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©Copyright 1996 Rogue Wave Software
The Queue Data Abstraction
As a data abstraction, a queue is traditionally defined as any object that implements the following
operations:
empty() return true if the collection is empty
size() return number of elements in collection
front() return (but do not remove) the element at the front of the queue
back() return the element at the end of the queue
push(newElement) push a new element on to the end of the queue
pop() remove (but do not return) the element at the front of the queue
Include Files
Note that the operations of accessing and of removing the front elements are performed separately.
Programs that use the queue data abstraction should include the file queue, as well as the include
file for the container type (e.g., list).
# include <queue>
# include <list>
Declaration and Initialization of queue
A declaration for a queue must specify both the element type as well as the container that will hold
the values. For a queue the most common containers are a
list or a deque . The list version is
generally smaller, while the deque version may be slightly faster. The following are sample
declarations for a queue.
queue< int, list<int> > queueOne;
queue< double, deque<double> > queueTwo;
queue< Part *, list<Part * > > queueThree;
queue< Customer, list<Customer> > queueFour;
The last example creates a queue of a programmer-defined type named Customer. As with the stack
container, all objects stored in a queue must understand the operators < and ==.
Because the queue does not implement an iterator, none of the generic algorithms described in
Sections
13 or 14 apply to queues.