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Editorial Team
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Asked: 2026-06-08T08:04:42+00:00

Do these two substitutions always yield the same results? $data =~ s/\p{Space}//g; $data =~

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Do these two substitutions always yield the same results?

$data =~ s/\p{Space}//g;

$data =~ s/[\h\v]//g;
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1 Answer

  1. Editorial Team

    Yes.

    $ diff -U0 \
      <( unichars -au '\p{Space}' ) \
      <( unichars -au '[\h\v]'    ) \
   && echo No differences
No differences

    Contrast with

    $ diff -U0 \
      <( unichars -au '\p{Space}' ) \
      <( unichars -au '\s'        ) \
   && echo No differences
--- /dev/fd/63  2012-07-20 11:28:33.356934588 -0400
+++ /dev/fd/62  2012-07-20 11:28:33.356934588 -0400
@@ -3 +2,0 @@
- ---- U+0000B LINE TABULATION

    \s might start including U+000B soon, though.

    unichars is installed by Unicode::Tussle.

    Note: Without /u or use 5.012;, \s sometimes doesn’t match NBSP.

    I just found a bug in Perl (5.16.0). Reporting it immediately.

    $ perl -le'print "\xA0" =~ /\p{Space}/ ?1:0'
1

$ perl -le'print "\xA0" =~ /\s/ ?1:0'
0

$ perl -le'print "\xA0" =~ /\s/u ?1:0'
1
                                         __
$ perl -le'print "\xA0" =~ /\h/ ?1:0'      \
1                                           \
                                             > huh??
$ perl -le'print "\xA0" =~ /[\h]/ ?1:0'     /
0                                        __/

$ perl -le'print "\xA0" =~ /[\h]/u ?1:0'
1

    So that means, no, \p{Space} and [\h\v] are only equivalent if /u or use 5.012; is used.

    Ticket #114220

    Status:

    • /\h/ is equivalent to /[\h]/ in 5.10, 5.12, 5.14 and 5.18
    • /\h/ is not equivalent to /[\h]/ in 5.16.0
    • Don’t know about 5.16.1
    • 0