Re: boolean IN(); function in perl like

There are several ways to do this. One of the easiest is grep:

if (grep {$_ eq $e} @a) {
  # $e is in @a
}
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However, if this is done many times and/or if @a gets to be too large, a hash lookup can be useful:

my %lookup = map { $_ => 1 } @a; # only do this once if you can
if (exists $lookup{$e}) {
  # $e is in @a
}
[download]

Cheers,
Ovid

New address of my CGI Course.

Comment on Re: boolean IN(); function in perl like Select or Download Code

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Re^2: boolean IN(); function in perl like by nobull (Friar) on Jan 15, 2005 at 11:03 UTC
`my %lookup = map { $_ => 1 } @a;` [download] There is no need to put values in the hash. `my %lookup; @lookup{@a}=();` [download] Futhermode if `@a` is holding a set of data that is not conceptually ordered it is better to simply use a hash and not an array in the first place.	[reply] [d/l] [select]
Re^2: boolean IN(); function in perl like by RhetTbull (Curate) on Jan 15, 2005 at 18:51 UTC
One word of caution when using grep -- it will find all occurrences of $e in @a so if @a is large or there are a lot of occurrences of $e it will take longer than just looking for the first occurrence. You might also want to look at the any function in List::MoreUtils.	[reply]