Re^3: lsearch for perl?

[ikegami]

While I agree that hashes wouldn't be too useful here (being unordered), I think of hashes as having three basic uses (not one):

• Unordered set of associations (Notice the plural var name)

  my %user_passwds = (
     joe  => ...,
     jeff => ...,
     john => ...,
  );
  

• Unordered set of properties (Notice the singular var name)

  my %user = (
     id       => 'joe',
     name     => 'Joe',
     passwd   => ...,
     home_dir => ...,
  );
  

• Uniqueness constraint

  my %unique;
  ++$unique{$_} foreach @list;
  @list = keys %unique;
  

[thor]

I meant association in a looser sense than you mention above. For the first set, you're associating passwords with their respective users. In the second set, you're associating the given values with their type ("joe" is the "id" for this user). As for the uniqueness condition, I agree that it's useful, but not a hash's intended use. Incidentally, I think that the following loop uses less memory:

my %unique;
$unique{$_} = undef foreach @list;
@list = keys %unique;

due to the undef being shared amongst all of the keys of the hash. That may be an urban legend that I heard somewhere, though. ;)

[ikegami]

I'm pretty sure undef uses less mem, and it's probably a bit faster, but ++ allows you to check which items had duplicates. undef @unique{@list}; is actually fastest.