What's the difference between an Algorithm and a Design Pattern

Question

I was searching for \"Undo/Redo algorithms\" and found something marked as a duplicate, but the duplicate was a request for a \"Undo Design Pattern\". I\'d really like an al

Answer 1

Yes, there is a difference.

An algorithm is a recipe for performing some task - an unambiguous finite set of instructions that achieves some goal by operating on an input and producing an output. Typically an algorithm is expressed in a language-agnostic pseudo-code, which can then be implemented in the language of your choice.

A design pattern is a way of structuring your code in order to elegantly express a relationship between functional components. You might use design patterns within the implementation of an algorithm. For example, you might use an algorithm for an in-order walk of a tree to ensure that you visit all the nodes of a tree data structure in a certain order. You might also implement a visitor design pattern to express how your implementation returns control to the calling context to indicate that a node has been visited. This is not part of the algorithm, but part of the software design, and how you structure the interfaces that each component of your software can use.

Algorithms and design patterns are orthogonal, although they may well both be used at the same time.