
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

Implement a FIFO queue.

Elements are added at one side and popped from the other in the order of insertion.



Operations:

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


Errors:

   handle the error of trying to pop from an empty queue (behavior depends on the language and platform)


See

   Queue/Usage   for the built-in FIFO or queue of your language or standard library.


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


 
# Project : Queue/Definition
 
load "stdlib.ring"
oQueue = new Queue 
for n = 5 to 7
     see "Push: " + n + nl
     oQueue.add(n) 
next
see "Pop: " + oQueue.remove() + nl
see "Push: 8" + nl
oQueue.add(8)
see "Pop: " + oQueue.remove() + nl
see "Pop: " + oQueue.remove() + nl
see "Pop: " + oQueue.remove() + nl 
if len(oQueue) != 0
   oQueue.print()
else
   see "Error: queue is empty" + nl
ok
 