Printing Perl Hash Keys

问题:

I am trying to print out my Hash Keys in Perl, one per line. How would I go about doing this?

回答1:

Does this do it for you?

print "$_\n" for keys %hash;

回答2:

Short version:

$, = "\n";
print keys %hash;

Or inside a larger script:

{
    local $, = "\n";
    print keys %hash;
}

To put it in a variable, for printing in a message box in accordance to your comments:

my $var = join "\n", keys %hash;

回答3:

We can done this by using map function.

map {print "$_\n"} keys %hash; 

map function process its statement for every keys in the hash.