keys
Returns all keys of a hash, or the number of keys in scalar context.
In list context, pushes all keys of the hash onto the stack as
individual string values. In scalar context, returns the number of
key-value pairs. Accepts both %hash and $hashref (auto-
dereferences). As a side effect, resets the hash’s internal
iterator used by each.
Synopsis
my @k = keys %hash;
my $count = keys %hash; # scalar context: number of keys
for my $key (keys %hash) { ... }
Implementation Notes
perl5: In scalar context, returns the number of keys. In list context, pushes all keys onto the stack.