\b

##</code><code>##

(?:(?<=\w)(?!\w)|(?<!\w)(?=\w))

##</code><code>##

(?:(?<=[\w-])(?![\w-])|(?<![\w-])(?=[\w-]))

##</code><code>##

my $my_slash_b = qr/(?:(?<=[\w-])(?![\w-])|(?<![\w-])(?=[\w-]))/;

/$my_slash_b$check$my_slash_b/

##</code><code>##

/(?<![\w-])$check(?![\w-])/

##</code><code>##

my $my_slash_b = qr/(?:(?<=\S)(?!\S)|(?<!\S)(?=\S))/;

/$my_slash_b$check$my_slash_b/

##</code><code>##

/(?<!\S)$check(?!\S)/