The Ruby Way: Solutions and Techniques in Ruby Programming, Second Edition

2.33. Generating Successive Strings

On rare occasions we may want to find the “successor” value for a string; for example, the successor for "aaa" is "aab" (then "aad", "aae", and so on).

Ruby provides the method succ for this purpose:

droid = "R2D2"
improved  = droid.succ         # "R2D3"
pill  = "Vitamin B"
pill2 = pill.succ              # "Vitamin C"

We don’t recommend the use of this feature unless the values are predictable and reasonable. If you start with a string that is esoteric enough, you will eventually get strange and surprising results.

There is also an upto method that applies succ repeatedly in a loop until the desired final value is reached:

"Files, A".upto "Files, X" do |letter|
  puts "Opening: #{letter}"
end

# Produces 24 lines of output

Again, we ...