in reply to in function?

This is best done using a hash instead of an array. But if you only have an array to begin with, it's easy to convert.
(Warning, untested code below)

# assume your array is still in myarray; set up a hash
foreach (@myarray) {
    $myhash{$_} = 1;
}

# now, test for the existence of 'blah'

if ($myhash{'blah'}) {
  do_something();
}

[download]
If you use a hash instead of an array everywhere, you can also save the one-time overhead of setting up the hash in the first place. Using a hash makes the test closer to unit time than linear, which can speed things up significantly if you have a lot of array elements, or if you're doing a lot of "in"-like tests.

Alan

Replies are listed 'Best First'.
RE: Re: in function?
by SuperCruncher (Pilgrim) on Jul 08, 2000 at 15:35 UTC
    A more succinct (but semantically equivalent) version of: 
    foreach (@myarray) {
      $myhash{$_} = 1;
}

    [download]
    is 
    $myhash{$_}++ for @myarray;

    [download]
    I once heard (somewhere) that doing 
    if ($myhash{'blah'}) {
    do_something();
}

    [download]
    (i.e. refering to a key in a hash) causes that key to come into existence, so the above expression may always evaluate as true. I haven't been able to prove this, but I think what you want is the exists function: 
    if (exists($myhash{'blah'})) { 
  # Do something here
}

    [download]
    I quite like using 'exists', it makes code far more readable.
[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom