
Data Structure

This illustrates a data structure, a means of storing data within a program.

You may see other such structures in the Data Structures category.
 Illustration of FIFO behavior
Task

Create a queue data structure and demonstrate its operations.

(For implementations of queues, see the FIFO task.)



Operations:

   push       (aka enqueue) - add element
   pop         (aka dequeue) - pop first element
   empty     - return truth value when empty


See also

 Array
 Associative array: Creation, Iteration
 Collections
 Compound data type
 Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
 Linked list
 Queue: Definition, Usage
 Set
 Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
 Stack


Empty[a_] := If[Length[a] == 0, True, False]
SetAttributes[Push, HoldAll]; Push[a_, elem_] := AppendTo[a, elem]
SetAttributes[Pop, HoldAllComplete]; Pop[a_] := If[EmptyQ[a], False, b = First[a]; Set[a, Most[a]]; b]
 
Queue = {}
-> {}
Empty[Queue]
-> True
Push[Queue, "1"]
-> {"1"}
EmptyQ[Queue]
->False
Pop[Queue]
->1
Pop[Queue]
->False