A loop cannot be avoided, but it can be implicit instead of coded longhand:

my @list = qw/ frog turtle tadpole /;
my $find = "turtle";

if( grep { $_ eq $find } @list ) {
    print "Found $find.\n";
}

[download]

This isn't going to be the fastest way to do it, because it iterates through the entire list, even if it finds $find as the first element. For randomly distributed data, a smarter algorithm would quit as soon as the first instance is found, like this:

my $found_flag = 0;
foreach my $item ( @list ) {
    if( $item eq $find ) {
        $found_flag = 1;
        last;
    }
}

if( $found_flag ) {
    print "Found $find.\n";
}

[download]

Either way, a loop is occurring. With grep, the loop happens behind the scenes. The second method spells it out explicitly, and tells it to exit as soon as the item you're looking for is found. That (on average) ought to be faster.

You could also use List::Util's first() subroutine, like this:

use List::Util;

my @list = qw/ this that other /;
my $find = "that";

if( first { $_ eq $find } @list ) {
    print "I found it!\n";
}

[download]

I'm not sure how first() is implemented, but it should be implemented such that it exists as soon as it finds the match.


Dave

In reply to Re: without looping, check if $var is found in @list by davido
in thread without looping, check if $var is found in @list by Anonymous Monk

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