Tag Archives: Recursion

Recursion as sophisticated GOTO?

Suppose you write a simple program to play a number guessing game: “I’m thinking of a whole number between X and Y…” where the user attempts to guess the number in order to win. Failures that require feedback to the user come in three main flavors:

  1. The user guessed incorrectly
  2. The user’s guess was out of range
  3. The user did something silly, like enter a non-integer value

The do..while form

You can do this with a loop, of course. A do..while loop seems like a natural choice here. What I don’t like is the validation and user feedback in the while clause. You’d call out to a method that hides all of the validation logic, and returns true or false. This is OK, but that boolean method will have a side effect, i.e. feedback to the user.

The recursive form

An alternative implementation might use recursion:

I find this second way to be more natural and readable. But it also feels like the wrong thing to do, though I can’t articulate why. Maybe it’s because any time I’ve seen code that followed this kind of pattern, I’ve seen it written using loops.