Recursion as a replacement for loops

Lord_Yggdrasill

Well recursion is a very powerful tool used in functions and methods, they play vital roles in programming languages in which loops are not available. Even for languages with decent support for loops, recursion still proves to be useful from cases to cases. I was wondering though, in which circumstances would you rather use recursion instead of loops? And is there a reason for preferring one over the other? Considering a situation in which you are mapping database information into model fields/properties, is it better to use recursion or loops?

laserlight

Lord Yggdrasill wrote:
in which circumstances would you rather use recursion instead of loops?

When the recursive version is more elegant, easier to understand, and the recursive depth or stack memory use will not cause a problem.

Lord Yggdrasill wrote:
And is there a reason for preferring one over the other? Considering a situation in which you are mapping database information into model fields/properties, is it better to use recursion or loops?

Generally, iteration should be preferred to avoid running into the problem of exceeding the maximum recursion depth. Related to this, iteration will likely be more efficient in memory usage, even if there must be the use of an explicit stack (since you can choose to save in the stack the necessary data and nothing else).

NogDog

I suspect (but have not tested/measured) that using a built-in looping mechanism will be faster, too, all other things being equal (which they seldom are 😉 ), since you'd then be using the compiled (and presumably optimized) mechanisms from the underlying C code, versus a user-defined PHP function to do the looping. Also, unless you're fairly verbose and descriptive with your function naming, using a built-in loop construct will likely do a better job of self-documenting, making it easier to tell at a glance at the source code that looping is occurring there.

Weedpacket

Recursive code would be more useful in the context of recursive data structures. Clever data and dumb code tends to trump dumb data and clever code.