Neither ' ', '&', nor ';' are word characters, so there is no word boundary between them.

On the other hand, 'a', and 'f' are word characters (and '&' and ';' still aren't), so there are your word boundaries.

You probably want either negative or positive lookahead/lookbehind for (non-)whitespace instead. Negative version: 

$str = 'abac ~~~ afa~~&#x0007E
+;f';
$str =~ s|(?<!\s)\&\#x0007E\;\&\#x0007E\;\&\#x0007E\;(?!\s)|~~~|g;
print $str;

[download]

Positive lookahead/lookbehind won't match at end/beginning of string: 

$str = 'abac &#x0007E;&#x0007E;&#x0007E; afa&#x0007E;&#x0007E;&#x0007E
+;f';
$str =~ s|(?<=\S)\&\#x0007E\;\&\#x0007E\;\&\#x0007E\;(?=\S)|~~~|g;
print $str;

[download]

print "Just another Perl ${\(trickster and hacker)},"
The Sidhekin proves Sidhe did it!

In reply to Re: Word boundary '\B' - Question by Sidhekin
in thread Word boundary '\B' - Question by prasadbabu

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