#! perl -slw
use strict;
my( @for ) = 
( 
qr[\w+\#],
qr[\w+ \# ]x,
qr[\w+ [#] ]x,
qr[\w+ \Q#\E ]x,
qr[\w+ \x23 ]x,
);

print for @for;


my $r = "the# stringy# the# dude# foy ";

print $r;

for my $s( @for ) {
    my( @m ) = $r =~ /$s/g;
    warn scalar @m;
}
__END__

# on 5.8
##########################
(?-xism:\w+\#)
(?x-ism:\w+ \#
)
(?x-ism:\w+ [#]
)
(?x-ism:\w+ \#\\E\
)
(?x-ism:\w+ \x23 )
the# stringy# the# dude# foy
4 at - line 21.
4 at - line 21.
4 at - line 21.
0 at - line 21.
4 at - line 21.

# on 5.6
##########################
(?-xism:\w+\#)
(?x-ism:\w+ \# )
(?x-ism:\w+ [#] )
(?x-ism:\w+ \#\\E\ )
(?x-ism:\w+ \x23 )
the# stringy# the# dude# foy
4 at - line 21.
4 at - line 21.
4 at - line 21.
0 at - line 21.
4 at - line 21.