up-and-down-with-integers.md

Up And Down With Integers

Ruby's Integer class comes with an #upto and a #downto method. Both of these methods can be used to iterate from one number up or down to, respectively, another number.

Let's count to 3

> 1.upto(3) { |x| puts x }
1
2
3

This of course can easily and perhaps more idiomatically be accomplished with a range and the #each method (e.g. (1..3).each { |x| puts x }.

We cannot, however, simulate the #downto method with a range (at least, not very cleanly). So, if you need to count down to something, this is going to be the cleanest and clearest way.

> 5.downto(2) { |x| puts x }
5
4
3
2

The return value for both methods is always the integer we started with.