Reg. length of anonymous array

[Balaji thoguluva]

Hi,

I am a novice to perl programming. I have a reference to a hash with a hash key as a reference to an anonymous array.

For clarity, I have something like this structure

my $rhash = {
$rarray => [ ],
};

I would like to know the length of the anonymous array containing some elements.

Thanks,
Balaji




Yahoo! India Education Special: Study in the UK now.

[David]

Balaji thoguluva wrote:

> For clarity, I have something like this structure
>
> my $rhash = {
> $rarray => [ ],
> };
>
> I would like to know the length of the anonymous array containing some
> elements.

the usual trick use be used:

#!/usr/bin/perl -w
use strict;

my $h = {array => [1,3,5,7]};

print @{$h->{array}} . "\n";
print $#{$h->{array}} . "\n";

__END__

prints:

4
3

david
--
sub'_{print"@_ ";* \ = * __ ,\ & \}
sub'__{print"@_ ";* \ = * ___ ,\ & \}
sub'___{print"@_ ";* \ = * ____ ,\ & \}
sub'____{print"@_,\n"}&{_+Just}(another)->(Perl)->(Hacker)

[David]

Balaji,
next time when you reply please send it reply to the whole group, don't just
sent it to myself. this gives the others a chance to help you.

On Thursday 12 February 2004 20:05, you wrote:

> Hi David,
>
> Thanks for your answer. It is working but I dont know what
> the dot operator signifies. I would appreciate if you could explain it
> or refer me to any documentation.

[snip]

> >
> > I would like to know the length of the anonymous array containing some
> > elements.

>
> the usual trick use be used:
>
> #!/usr/bin/perl -w
> use strict;
>
> my $h = {array => [1,3,5,7]};
>
> print @{$h->{array}} . "\n";
> print $#{$h->{array}} . "\n";
>

the dot operator does 2 things in this example:

1. it concatenates the two operants and creates a string out of them.
2. it forces both operants to be in scalar context.

the second point is important, consider:

print @{$h->{array}},"\n";
print $#{$h->{array}},"\n";

without the dot operator, it prints:

1357
3

because @{$h->{array}} is taken in list context by the 'print' function.

david
--
sub'_{print"@_ ";* \ = * __ ,\ & \}
sub'__{print"@_ ";* \ = * ___ ,\ & \}
sub'___{print"@_ ";* \ = * ____ ,\ & \}
sub'____{print"@_,\n"}&{_+Just}(another)->(Perl)->(Hacker)

[Shiping]

Hi,

How can I rearrange an array in a specific order based on the order of a
hash? Something like this:

my @a = qw(Mary John Dan);
print join "\t", @a, "\n";

my %b = ( John => 0,
Dan => 1,
Mary => 2);
print "$_ => $b{$_}\n" for (keys %b);

print "$_-$b{$_}\t" foreach sort {$b{$a} <=> $b{$b}} keys %b;

The final order for @a expect:

John Dan Mary

Thanks,

Shiping