How to loop through each character in a Ruby String

Ruby character/string FAQ: How can I loop through each character in a Ruby String, and perform some operation on each character?

I'm currently using Ruby 1.8.6, and you can use the Ruby each_char method if you'll first require the jcode module. To be clear, this code will not work in Ruby 1.8.6:

a = 'hello, world'
a.each_char { |c|
  puts c
}

In fact it results in the following error:

each-char.rb:4: undefined method `each_char'
for "hello, world":String (NoMethodError)

However, if you first require the jcode library, the following code will work:

require 'jcode'

a = 'hello, world'
a.each_char { |c|
  puts c
}

For the record, that code generates the following output:

h
e
l
l
o
,
 
w
o
r
l
d

Discussion

This feature may be modified in future versions of Ruby, but that's the way it works today. Here's a link to a brief discussion about this issue.