preending

Preending is a term used in computer science and programming to describe the operation of adding an element to the beginning of a data structure. This is distinct from appending, which adds an element to the end. Preending is a fundamental operation for many sequential data structures, such as linked lists and queues.

In the context of a linked list, preending involves creating a new node containing the element to be added and then updating the head pointer of the list to point to this new node. The new node's next pointer would then be set to point to the original head of the list. This operation is typically very efficient, often taking constant time, denoted as O(1), as it only requires a few pointer manipulations.

Similarly, in a queue implemented using a linked list, preending can be used to add elements to the front. However, in a standard queue where elements are removed from the front (dequeue) and added to the back (enqueue), preending to the front would be an unusual operation unless the queue's behavior is modified to be a deque (double-ended queue).

Data structures like arrays or dynamic arrays generally do not support efficient preending. Adding an element to the beginning of an array usually requires shifting all existing elements one position to the right to make space for the new element, resulting in a time complexity of O(n), where n is the number of elements in the array. This inefficiency often leads developers to choose alternative data structures like linked lists when frequent preending operations are anticipated.