Re: Re: Re: Re: Re: Simple hash assignment...or is it?

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Re: Simple hash assignment...or is it? by liz (Monsignor) on Nov 22, 2003 at 10:14 UTC
To print the values in a hash, use the keys keyword. my %hash = ( 'a' => 1, 'b' => 2, 'c' => 3); foreach (keys %hash) { print "$_ => $hash{$_}\n"; } Cheers. :-) In general, I wouldn't say that. "keys" is a standard Perl function (not a keyword), of which you can omit the () because there is a prototype known for it. Furthermore: If you want the values of a hash in no particular order as a list, use the values function. `my @value = values %hash;` [download] If you want the keys of a hash in no particular order as a list, use the keys function. `my @key = keys %hash;` [download] If you want either the values or keys in a particular order, use sort() as well. `my @value = sort values %hash; my @key = sort keys %hash; foreach (sort keys %hash) { print "$_ => $hash{$_}\n"; }` [download] If you want to show the keys and possibly the associated values in no particular order, use each. `while (my $key = each %hash) { print "$key\n"; } while (my ($key,$value) = each %hash) { print "$key => $value\n"; }` [download] The reason for using each() over keys(), is that keys() (and values()) build a list of the values. For large hashes, this list can get very big and cosume a lot of memory. You don't have that when you're using each(), as it will only fetch one key or one key/value pair from the hash at a time. Liz	[reply] [d/l] [select]

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Re: Simple hash assignment...or is it?
by liz (Monsignor) on Nov 22, 2003 at 10:14 UTC

To print the values in a hash, use the keys keyword. my %hash = ( 'a' => 1, 'b' => 2, 'c' => 3); foreach (keys %hash) { print "$_ => $hash{$_}\n"; } Cheers. :-)

function

If you want the values of a hash in no particular order as a list, use the values function.
```
my @value = values %hash;
[download]
```
If you want the keys of a hash in no particular order as a list, use the keys function.
```
my @key = keys %hash;
[download]
```

If you want either the values or keys in a particular order, use sort() as well.

my @value = sort values %hash;
my @key = sort keys %hash;
foreach (sort keys %hash) {
    print "$_ => $hash{$_}\n";
}
[download]

If you want to show the keys and possibly the associated values in no particular order, use each.

while (my $key = each %hash) {
    print "$key\n";
}
while (my ($key,$value) = each %hash) {
    print "$key => $value\n";
}
[download]

Liz

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