Re: How to I check if a value is present in an array?

grep doesn't do what you think. It returns a list of all elements where the search expression is true. The search expression in your case is $genes[$index], so if that's a true value, grep returns all the elements of @gl.

What you probably want to write instead is something like

for my $current (@genes) {
    if (grep { $_ eq $current } @gl) {
         print $current;
    }
}
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Though of course if either (or both) of these arrays is large, that is rather inefficient, and you might consider storing stuff in a hash in the first place.

Perl 6 - the future is here, just unevenly distributed

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Re^2: How to I check if a value is present in an array? by Tux (Canon) on Aug 03, 2013 at 12:17 UTC
If `@gl` is (or can be) large/huge, List::Util's `first` can be an important speedup. `use List::Util qw( first ); for my $current (@genes) { say $current if first { $_ eq $current } @gl; }` [download] Enjoy, Have FUN! H.Merijn	[reply] [d/l] [select]