.. efun:: int regexp_package()
  :include: <regexp.h>

  Return which regexp package is used by default:

    :macro:`RE_TRADITIONAL`: traditional regexps
    :macro:`RE_PCRE`:        PCRE

  As the package can be selected at runtime through the :hook:`H_REGEXP_PACKAGE` driver hook, there is no good way to determine the package at LPC compile time. Match the pattern <pattern> (interpreted according to <opt> if given) against all strings in list, and return a new array with all strings that matched.

  .. todo:: the last sentence above and the one below both seem out of place?

  If there is an error in the regular expression, a runtime error will be raised.

  .. usage::

    This example uses a regular expression to test the given string (which is packed into an array) if there is something like "help ... me" inside of it::

      string strs;
      string pattern;

      if (regexp_package() == RE_PCRE)
          pattern = "\\<help\\>.*\\<me\\>";
      else
          pattern = "\\bhelp\\b.*\\bme\\b";

      if (strs = regexp(({"please, help me Sir John."}), pattern)) {
          if (sizeof(strs)
              write("It matches.\n");
      }

  :history 3.3.634 introduced:

  .. seealso:: :efun:`regexp`, :efun:`regexplode`, :efun:`regmatch`, :efun:`regreplace`, :efun:`sscanf`, :concept:`regexp`, :hook:`regexp_package`