Recursion When to use it?

Question

So we just finished the subject recursion in school and I am still wondering "why?".

I feel like I have just learned a hell of a lot about math in a programming way with the sole purpose of passing an exam later on and then never again.

So what I want to know is when to use it? I can only find people saying "when you want to call a function within itself" but why would you do that?

[What is recursion and when should I use it?](http://stackoverflow.com/questions/3021/what-is-recursion-and-when-should-i-use-it) — Alex K., Mar 01 '16 at 13:38

score 2 · Accepted Answer · answered Mar 01 '16 at 13:36

Recursion is the foundation of computation, every possible program can be expressed as a recursive function (in the lambda calculus). Hence, understanding recursion gives you a deeper understanding of the principles of computation.

Second, recursion is also a tool for understanding on the meta level: Lots of proofs over the natural numbers follow a pattern called "natural induction", which is a special case of structural induction which in turn allows you to understand properties of very complex systems in a relatively simple way.

Finally, it also helps to write good (i.e. readable) algorithms: Whenever there is data to store/handle in a repetitive calculation (i.e. more than incrementing a counter), you can use a recursive function to implicitly manage a stack for you. This is also often very efficient since most systems come with a machine stack at hand.

How about accepting my answer? – choeger Mar 01 '16 at 14:26 — choeger, Mar 01 '16 at 14:26

Recursion When to use it?

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