String has been split using punctuation as delimiters; how to reassemble and put the punctuation back in?

Question

Im implementing a profanity filter by using a Trie data structure. Every swear word is added to the Trie. When I have a string to remove profanities from, I explode the string by using punctuations and check every word with the Trie. If found I replace by asterisks.Then I implode the string The issue is, how do I keep track of punctuations? In other words how do I make sure the resultant string has punctuations?

Answer 1

If you are using preg_split() to split up your string, consider using the PREG_SPLIT_DELIM_CAPTURE flag to capture the punctuation with the matches.

Consider:

$str = "This. string/ has? punctuation!";
print_r(preg_split('/(\W+)/', $str, -1, PREG_SPLIT_DELIM_CAPTURE));

/*
  Array
  (
      [0] => This
      [1] => . 
      [2] => string
      [3] => / 
      [4] => has
      [5] => ? 
      [6] => punctuation
      [7] => !
      [8] => 
  )
*/

See http://php.net/preg_split for more information.