Source code in the pl/i programming language

Nth: procedure options (main);   /* 1 June 2014 */
   declare i fixed (10);

   do i = 0 to 25, 250 to 265, 1000 to 1025;
      if i = 250 | i = 1000 then put skip (2);
      put edit (enth(i)) (x(1), a);
   end;

enth: procedure (i) returns (character (25) varying);
   declare i fixed (10);
   declare suffix character (2);

   select (mod(i, 10));
      when (1)  suffix = 'st';
      when (2)  suffix = 'nd';
      when (3)  suffix = 'rd';
      otherwise suffix = 'th';
   end;
   select (mod(i, 100));
      when (11, 12, 13) suffix = 'th';
      otherwise ;
   end;
   return ( trim(i) || suffix );
end enth;

end Nth;