How do I perform an operation on every other character on a string?

Question

How do I capitalize only a string's even letters?

I've tried:

str = "apples"; str.capitalize

Answer 1

"abcdefgh".gsub /..?/, &:capitalize
=> "AbCdEfGh"

"abcdefgh".gsub /(?!^)..?/, &:capitalize
=> "aBcDeFgH"

Use string.gsub! instead of string.gsub if you want to modify your original string.

Answer 2

string.scan(/..?/).map(&:capitalize) * ''