Re^2: how can i return the common keys from a hash


P is for Practical
	PerlMonks

Re^2: how can i return the common keys from a hash

by ivancho (Hermit)

on Aug 05, 2006 at 01:19 UTC ( [id://565771]=note: print w/replies, xml )

Need Help??

in reply to Re: how can i return the common keys from a hash
in thread how can i return the common keys from a hash

I am somewhat puzzled by the following DWIM:

in scalar context, each returns the next key of the hash. Why doesn't, then, the assignment "my $m = each %$href" return false if the key is "0"? ie

> perl -wle 'my %a = ( 0 => 1, y => 2, z => 4); while (my $m = each %a
+) { print $m }'
y
0
z
> perl -wle 'my @a = ( 0 => 1, y => 2, z => 4); while (my $m = pop @a)
+ { print $m }'
4
z
2
y
1
> perl -wle 'my @a = ( 0 => 1, y => 2, z => 4); while (my $m = shift @
+a) { print $m }'
>
[download]

Comment on Re^2: how can i return the common keys from a hash Select or Download Code

Replies are listed 'Best First'.
Re^3: how can i return the common keys from a hash by imp (Priest) on Aug 05, 2006 at 01:42 UTC
`perl -MO=Deparse -wle 'my %a = ( 0 => 1, y => 2, z => 4); while (my $m + = each %a) { print $m }' BEGIN { $^W = 1; } BEGIN { $/ = "\n"; $\ = "\n"; } my(%a) = (0, 1, 'y', 2, 'z', 4); while (defined(my $m = each %a)) { print $m; }` [download] It checks for defined as the loop condition, not a true value.	[reply] [d/l]
Re^4: how can i return the common keys from a hash by ivancho (Hermit) on Aug 05, 2006 at 02:07 UTC
indeed, as that's what you want in 99% of the cases.. I was mostly pointing out that it's neither logical, nor obvious from docs	[reply]

In Section Seekers of Perl Wisdom

Domain Nodelet^?

www.com | www.net | www.org

Node Status^?

node history
Node Type: note [id://565771]
help

Chatterbox^?

How do I use this? • Last hour • Other CB clients

Other Users^?

Others meditating upon the Monastery: (3)

As of 2024-04-23 23:51 GMT

Sections^?

Information^?

Find Nodes^?

Leftovers^?

Today I Learned

Voting Booth^?

No recent polls found