(data structure)

Definition: A collection of items in which only the earliest added item may be accessed. Basic operations are add (to the tail) or enqueue and delete (from the head) or dequeue. Delete returns the item removed. Also known as "first-in, first-out" or FIFO.

Formal Definition: It is convenient to define delete or dequeue in terms of remove and a new operation, front. The operations new(), add(v, Q), front(Q), and remove(Q) may be defined with axiomatic semantics as follows.

  1. new() returns a queue
  2. front(add(v, new())) = v
  3. remove(add(v, new())) = new()
  4. front(add(v, add(w, Q))) = front(add(w, Q))
  5. remove(add(v, add(w, Q))) = add(v, remove(add(w, Q)))
where Q is a queue and v and w are values.

Also known as FIFO.

Generalization (I am a kind of ...)
abstract data type.

Specialization (... is a kind of me.)
bounded queue.

See also deque, stack, priority queue, first come, first served.

Author: PEB


Maksim Goleta's C# Collections linked-list implementation (C#). Bro. David Carlson's tutorial and code (C++) using linked list.
Go to the Dictionary of Algorithms and Data Structures home page.

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Entry modified 14 December 2020.
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Cite this as:
Paul E. Black, "queue", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed. 14 December 2020. (accessed TODAY) Available from: