$re = '/INDEXNAME\d*/';
$str = 'Schema="[dbo]" Table="[TABLENAME]" Index="[INDEXNAME1]" IndexKind="NonClustered"/>
Schema="[dbo]" Table="[TABLENAME]" Index="[INDEXNAME3]" IndexKind="NonClustered"/>
Schema="[dbo]" Table="[TABLENAME]" Index="[INDEXNAME18]" IndexKind="NonClustered"/>
Schema="[dbo]" Table="[TABLENAME]" Index="[INDEXNAME22]" IndexKind="NonClustered"/>
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php