The necessity of the FIFO principle in applications like printer spooling illustrates the reliable, fair resource management enabled by the Queue data structure. Now, we place the Queue in context alongside the other primary linear collection: the Stack.
Both the Stack and the Queue are fundamental linear data structures that manage elements sequentially. Despite their differing access patterns, both are highly efficient, designed to allow their primary manipulation operations to execute in constant time, or $O(1)$, regardless of the capacity (MAX_SIZE).
| Feature | Stack | Queue |
|---|---|---|
| Access Principle | Last In, First Out (LIFO) | First In, First Out (FIFO) |
| Insertion Op. | push() (Accesses the Top) |
enQueue() (Accesses the rear) |
| Removal Op. | pop() (Accesses the Top) |
deQueue() (Accesses the front) |
| Pointer(s) Used | Single pointer (top) |
Two pointers (front, rear) |
| Key Efficiency | $O(1)$ | $O(1)$ |