# read this from bottom to top (be sure to read 'perldoc -f map' first)
print # print will print the list that is returned from map
map { # map returns the last evaluated statement
"$_" . # this is what $_ was
":\t" . # this is a colon followed by a tab
# $h->{$_}[0] is the first element
of that array
# $h->{$_} points to an array ref
$h->{$_}[0] . # $_ is each key from hash ref $h
"\n" # this is a new line
} keys %{ $h }; # get the keys from hash ref $h
> -----Original Message-----
> From: Jerry Preston [mailto:g-preston1@;ti.com]
> Sent: Monday, October 21, 2002 5:20 PM
> To: Beginners Perl
> Subject: lost - map { "$_:\t$h->{$_}[0]\n"} keys %$h
>
>
> Hi!
>
> Can anyone explain to me how map works in this code?
>
> for my $h (
>
> # grab the Subject and Date from every message in my
> (fictional!) smut
> folder;
> # the first argument is a reference to an array listing
> all messages in
> the folder
> # (which is what gets returned by the $imap->search("ALL")
> method when
> called in
> # scalar context) and the remaining arguments are the
> fields to parse out
>
> # The key is the message number, which in this case we
> don't care about:
> values %{$imap->parse_headers(
> scalar($imap->search("ALL")) , "Subject",
> "Date")}
> ) {
> # $h is the value of each element in the hash ref returned from
> parse_headers,
> # and $h is also a reference to a hash.
> # We'll only print the first occurance of each field
> because we don't
> expect more
> # than one Date: or Subject: line per message.
> print map { "$_:\t$h->{$_}[0]\n"} keys %$h ;
> }
>
> How can I access this and break it done to look at each line?
>
> Thanks,
>
> Jerry
>
>
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