title: Any perl standard library to check if a string contains a given substring
body: <p>Given a query, I would like to check if this contains a given substring (can contain more than one word) . But I don't want exhaustive search, because this substring can only start a fresh word.</p>
  
  <p>Any perl standard libraries for this, so that I get something efficient and don't have to reinvent the wheel?</p>
  
  <p>Thanks,</p>