Creates a new RegexIterator that filters all entries whose key starts with 'test'.
<?php
$test = array ('str1' => 'test 1', 'teststr2' => 'another test', 'str3' => 'test 123');
$arrayIterator = new ArrayIterator($test);
$regexIterator = new RegexIterator($arrayIterator, '/^test/');
$regexIterator->setFlags(RegexIterator::USE_KEY);
foreach ($regexIterator as $key => $value) {
echo $key . ' => ' . $value . "\n";
}
?>
The above example will output: