Re: better way to find list members?

This is from Perlfaq.com.

  @animals = qw(cat dog bat rat gerbil snake pig chicken);

  foreach (@animals) { $animals{$_}++; }  # initialize %animals hash

  # use a hash
  if (exists $animals{'pig'}) {
    print "We have a pig!\n";
  }  

  # use grep
  if (grep { $_ eq 'snake'} @animals) {
    print "We have a snake!\n";
  }

  # use a for loop
  for (@animals) {
    last if $_ eq 'dog';
  }
  print "We have a dog!\n";
[download]

Cheers,
KM

Comment on Re: better way to find list members? Download Code

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RE: Re: better way to find list members? by DrManhattan (Chaplain) on Oct 18, 2000 at 03:35 UTC
`foreach (@animals) { $animals{$_}++; } # initialize %animals hash` [download] Here's a faster way to do that (looks neat too): `@animals{@animals} = (1) x @animals;` [download] It's not exactly the same since it's setting each hash member to 1 instead of ++'ing it, but that's no big deal if you're just checking for an element's existance. -Matt	[reply] [d/l] [select]
RE: RE: Re: better way to find list members? by runrig (Abbot) on Oct 18, 2000 at 03:58 UTC
If all you want is existence, then this: `@animals{@animals}=undef; print "Got a dog!\n" if exists $animals{dog};` [download] is faster and uses less memory.	[reply] [d/l]
RE: RE: Re: better way to find list members? by myocom (Deacon) on Oct 18, 2000 at 03:38 UTC
Are you sure you meant to do `@animals{@animals}`? That code seems fraught with peril... Update: Actually, the more I look at it, the more it's starting to possibly make some sense to me...	[reply] [d/l]
RE: Re: better way to find list members? by runrig (Abbot) on Oct 18, 2000 at 03:56 UTC
`foreach (@animals) { $animals{$_}++; } # initialize %animals hash # could be $animals{$_}++ for @animals;` [download] Regarding: `# use a for loop for (@animals) { last if $_ eq 'dog'; } print "We have a dog!\n";` [download] That'll always print 'We have a dog!', even when we don't.	[reply] [d/l] [select]