editi has asked for the wisdom of the Perl Monks concerning the following question:

Monks, 
$count = 0;
    s{((whom?)ever)}{
        ++$count == 5       # is it the 5th?
                ? "${2}soever"    # yes, swap
                : $1        # renege and leave it there
        }ige;

[download]
Thank you

Replies are listed 'Best First'.
Re: Please tell me the meaning of this code.
by cLive ;-) (Prior) on Jul 01, 2007 at 09:34 UTC
    Change the 5th occurrence of whoever/whomever in $_ to whosoever/whomsoever. Here's a little more detail in a slight rewrite: 
    my $count=0;
$_ =~ s/ ((whom?)ever)          # whom? is in $2, whom?ever is in $1
       / if ( ++$count == 5 )   # for the fifth match
         {
             "${2}soever";      # set to whom?soever
         }
         else
         {
             $1;                # leave it as it is
         }
       /igex; # case (i)nsensitive, (g)lobal match, (e)xecute replace 
+string.
           # (x) ignore whitespace (added for this code example)

    [download]
    ps - I hope your tutor reads Perlmonks :)
[reply]
[d/l]
Re: Please tell me the meaning of this code.
by shmem (Chancellor) on Jul 01, 2007 at 10:26 UTC
    This is basically a s/ubsti/tute/ operation (see Regexp Quote Like Operators operator, regexp in perlop) with the modifiers ige but in alternative syntax: the /patten/replacement/ elements get delimited with braces s{}{}, then the substitution is broken up with whitespace for better readability. The susbtitution part is actually a piece of code executed when the pattern is found, and which result gets interpolated for the pattern. That's what the e modifier stands for.

    --shmem 

    _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
[reply]
[d/l]
[select]
Re: Please tell me the meaning of this code.
by ForgotPasswordAgain (Vicar) on Jul 02, 2007 at 10:06 UTC
    The meaning.... mu?
[reply]

Back to Seekers of Perl Wisdom