Sort a text string by last word before separator

Given a text string: $OK = "Joe Blow, William Howard Anser, Hannie Jansen, etc, etc,"; $_SESSION['txt'] = "$OK"; session_write_close(); $txt = $_SESSION['txt']; $sorted = explode(", ", $txt); sort($sorted); print "$sorted"; results in a sort based on the first name: "Hannie Jansen, Joe Blow, William Howard Anser, etc, etc" I tried a another function (before_last) ****** function before ($this, $inthat) { return substr($inthat, 0, strpos($inthat, $this)); } function strrevpos($instr, $needle) { $rev_pos = strpos (strrev($instr), strrev($needle)); if ($rev_pos===false) return false; else return strlen($instr) - $rev_pos - strlen($needle); }; function after_last ($this, $inthat) { if (!is_bool(strrevpos($inthat, $this))) return substr($inthat, strrevpos($inthat, $this)+strlen($this)); }; function before_last ($this, $inthat) { return substr($inthat, 0, strrevpos($inthat, $this)); }; ******** to sort on last name, and it does work, but gives only the last item: $test2 = between_last(' ', ', ', $OK); print "$test2"; "Jansen" How would I get this 'before_last' function to iterate through the initial string, so I could build a sorted list with both first and last names, sorted by last name? I can't seem to get a proper 'foreach' statement to work, nor a 'while' statement. I'm really confused. I've read almost every entry on arrays/strings and searched code snippets. Almost all focus on one element arrays such "apple, orange, peach" rather than 2 or more elements such as "fancy cars, big trucks, fast dangerous motorcycles," Is it even possible to accomplish this type sort on a string? Any advice, pointers, or help will be greatly appreciated, Tia, Andre