s/(\d+)([st|nd|rd|th])+/num2en_ordinal($1)/ge;

The  | ordered alternation metacharacter is not meta in a character class. The character class [st|nd|rd|th] is equivalent to [stndrh|] (update: because repeated characters have no special significance in a class). The quantified capture group ([st|nd|rd|th])+ matches any of the characters in the [stndrh|] class one or more times and captures the last such character matched. Try matching against  '2ds' '33hn' '123|s' and a few other such strings. You may want something like the true alternation (?:st|nd|rd|th) possibly supported by some look-around assertions. 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = '1ds rule: 22hn, 3rd and 123|sdnfloor';
 ;;
 printf qq{'$&' } while $s =~ m{(\d+)([st|nd|rd|th])+}xmsg;
"
'1ds' '22hn' '3rd' '123|sdn'

[download]

Update: Maybe something like this: 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $rx_ordinal_indicator =
   qr{ (?<! [[:alpha:]]) (?: st | nd | rd | th) (?! [[:alpha:]]) }xms;
 ;;
 my $s = '1ds rule: 22hn, 2 then 3rd and 44 th, 2  nd of the 123|sdnfl
+oor';
 ;;
 printf qq{'$&'  } while $s =~ m{ (\d+) \s* $rx_ordinal_indicator }xms
+g;
"
'3rd'  '44 th'  '2  nd'

[download]
(Ordinarily, I wouldn't use  $& and friends, but it's convenient for this example.)

Give a man a fish:  <%-{-{-{-<

In reply to Re^2: replace all numerics to words in a txt file -- oneliner by AnomalousMonk
in thread replace all numerics to words in a txt file by imhacked

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