Getting the Twitter account from various input formats I have an input for users to enter a Twitter account in any different way and I want to extract the user account.

For example:

twitters = [
    "www.twitter.com/twitteruser1",
    "@twitteruser2",
    "twitteruser3",
    "https://twitter.com/twitteruser4",
    "https://www.twitter.com/twitteruser5",
    "www.twitter.com/twitteruser6",
    "http://www.twitter.com/twitteruser7",
    "http://www.twitter.com/twitteruser8",
    "twitter.com/twitteruser9"
]


The script that I've written to extract the data is the following:

twitters.each do |twitter|
    # for the url
    twitter_user = twitter.match(/twitter.com\/([^\/.]*)$/)
    if twitter_user != nil
        puts twitter_user[1]
        next
    end

    # for @ beginning
    twitter_user = twitter.match(/^@([^\/.]*)$/)
    if twitter_user != nil
        puts twitter_user[1]
        next
    end

    # if we arrive, we haven't found any coincidence
    puts twitter

end


It actually works, outputting the following:

twitteruser1
twitteruser2
twitteruser3
twitteruser4
twitteruser5
twitteruser6
twitteruser7
twitteruser8
twitteruser9


But as I'm really newbie in Ruby I wanted to check for possible improvements.
You can use a ruby case statement to check for different regex matches.  If a match is found, it is by definition not nil, so it removes the need for a nil check as well.

twitters.each do |twitter|
  case twitter
    # for the url
    when /twitter.com\/([^\/.]*)$/
      puts $1

    # for @ beginning
    when /^@([^\/.]*)$/
      puts $1

    # if we arrive, we haven't found any coincidence
    else
      puts twitter
  end
end


When ruby does a regex match, any capture groups are assigned to the global variables $1, $2, $3, and so on.  See this question on StackOverflow for more details about the mechanic.

Note on your regex: If you want the capture groups to actually contain anything, you should change the asterisk to a plus: ([^\/.]+).  Without the plus, "www.twitter.com/" will be captured by one of the regex.  With the plus, that string will fall into the default case.