preg_match

• We match a pattern in Ruby strings using the match method. Ruby’s match method works differently than preg_match in how it returns matches. We usually want to know two different things when we match data: If the pattern matched, and what specific strings sections were matched.

  PHP returns an integer to tell us if the data matched (either 0 or 1) and populates a matches array by reference. Ruby returns a MatchData object when the pattern matches, and nil when something doesn’t. We can inspect the MatchData object to find the actual string matches.

  In this example, we try to match the different components of a list of email addresses. Both preg_match and String#match only match the first occurrence of the pattern.

  PHP

  $string = 'joe@example.com; walter@example.org';
  $result = preg_match('/([a-z0-9_.-]+)@([a-z0-9-]+)\.([a-z.]+)/i', 
            $string, $matches);
  var_export($result); 
  // => 1
   
  var_export($matches); 
  // => array('joe@example.com', 'joe', 'example', 'com')

  Ruby

  string = 'joe@example.com; walter@example.org'
  matches = string.match(/([a-z0-9_.-]+)@([a-z0-9-]+)\.([a-z.]+)/i)
  p !matches.nil?
  # => true
   
  p matches
  # => #<MatchData:0x1ed138>
   
  p matches[1]
  # => "joe"
   
  p matches.to_a
  # ["joe@example.com", "joe", "example", "com"]

  see also

  • preg_match_all
  • preg_replace
  • preg_split

Looking for Rails or PHP web application development, integration, and training?

Rails for PHP is brought to you by Maintainable Software. Get custom web applications and personalized training from the authors of the book and website.