Need listthisdir() or similar.  It's quite common to put received files that have been processed correctly in a subdirectory called 'newfiles\ok', and those that failed in 'newfiles\error', and in that case you often don't want to know about files currently in the subdirectories.

char[][] listdir(char[] path, filter x) { return listdir(path, x, true); }
char[][] listthisdir(char[] path, filter x) { return listdir(path, x, false); }

char[][] listdir(char[] path, filter x, bool recurse)
{
 ...
}