The C++ Queue is a container adapter that gives the programmer a FIFO (first- in, first-out) data structure.
| Constructors | construct a new queue |
| back | returns a reference to last element of a queue |
| empty | true if the queue has no elements |
| front | returns a reference to the first element of a queue |
| pop | removes the first element of a queue |
| push | adds an element to the end of the queue |
| size | returns the number of items in the queue |