(PHP 5 >= 5.2.0)
RegexIterator::setPregFlags — Sets the regular expression flags.
$preg_flags
   )Sets the regular expression flags.
preg_flagsThe regular expression flags. See RegexIterator::__construct() for an overview of available flags.
No value is returned.
Example #1 RegexIterator::setPregFlags() example
Creates a new RegexIterator that filters all entries with where the array key starts with 'test'.
<?php
$test = array ('test 1', 'another test', 'test 123');
$arrayIterator = new ArrayIterator($test);
$regexIterator = new RegexIterator($arrayIterator, '/^test/', RegexIterator::GET_MATCH);
$regexIterator->setPregFlags(PREG_OFFSET_CAPTURE);
foreach ($regexIterator as $key => $value) {
    var_dump($value);
}
?>
The above example will output something similar to:
array(1) {
  [0]=>
  array(2) {
    [0]=>
    string(4) "test"
    [1]=>
    int(0)
  }
}
array(1) {
  [0]=>
  array(2) {
    [0]=>
    string(4) "test"
    [1]=>
    int(0)
  }
}