'test' で始まるすべての文字列を取り出す新しい RegexIterator を作成します。
    
<?php
$rArrayIterator = new RecursiveArrayIterator(array('test1', array('tet3', 'test4', 'test5')));
$rRegexIterator = new RecursiveRegexIterator($rArrayIterator, '/^test/',
    RecursiveRegexIterator::ALL_MATCHES);
foreach ($rRegexIterator as $key1 => $value1) {
    if ($rRegexIterator->hasChildren()) {
        // すべての子を表示します
        echo "Children: ";
        foreach ($rRegexIterator->getChildren() as $key => $value) {
            echo $value . " ";
        }
        echo "\n";
    } else {
        echo "No children\n";
    }
}
?>
     
    
No children
Children: test4 test5