PHP function to create ordinal suffixes.

an_ordinal.php

<?php
  // Disclaimer: This is not the most modern method of doing this.
  function ordinal($num) {
    $test = abs($num) % 10;
    $suffix = ((abs($num) %100 < 21 && abs($num) %100 > 4) ? 'th'
            : (($test < 4) ? ($test < 3) ? ($test < 2) ? ($test < 1)
            ? 'th' : 'st' : 'nd' : 'rd' : 'th'));
    return $num.$suffix;
}

// usage
$day = 10;
echo ordinal($day); //output is 10th

license.txt

Copyright 2018 Hendrik Eduard Kuiper

Permission is hereby granted, free of charge, to any person obtaining a 
copy of this software and associated documentation files (the "Software"), 
to deal in the Software without restriction, including without limitation the 
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 
sell copies of the Software, and to permit persons to whom the Software is 
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in 
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 
ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.