Get Suffix of Given Number/Date

function get_suffix($number) {

   $last_number = substr($number,-1); //fetch the last number

   if($last_number == "0" || $last_number == 0){ $last_number = 4; } // if last number is 0 than it assign value 4
      return date("S",mktime(0,0,0,1,$last_number,2009));
}

Returns suffix of any number:
1 = st
2 = nd
3 = rd
4 = th
50 = th

Example: This is the 23rd coolest snippet ever.

Return date of month with appropriate suffix

function day_of_month(  ) {
        $number = date( 'j' );
        if ( $number[( strlen( $number ) - 1 )] == 1 ) {
                $suffix = "st";
        } elseif ( $number[( strlen( $number ) - 1 )] == 2 ) {
                $suffix = "nd";
        } elseif ( $number[( strlen( $number ) - 1 )] == 3 ) {
                $suffix = "rd";
        } else {
                $suffix = "th";
        }
        return array( "number" => $number, "suffix" => $suffix );
}