How does Ruby detect a carriage return in a string?

Question

I'm iterating through a large string that has several carriage returns. I'd like my logic to do something every time a carriage return is discovered (create a new ActiveRecord instance with all the string content before the carriage return).

Answer 1

def doit(str)
  start_idx = 0
  while i = str.index("\n", start_idx)
    action str[0..i-1]
    start_idx = i+1
  end
end

def action(str)
  puts "This is what I've read: #{str}"
end

doit("Three blind mice,\nsee how they run.\nThey all ran after the farmer's wife\n")
  # This is what I've read: Three blind mice,
  # This is what I've read: Three blind mice,
  # see how they run.
  # This is what I've read: Three blind mice,
  # see how they run.
  # They all ran after the farmer's wife

See String#index.

If you only want to pass the portion of the string since the previous newline, change the line:

action str[0..i-1]

to:

action str[start_idx..i-1]