Hi, i'm a little confused with the following examples of grep, all these while i thought grep's 2nd parameter is supposed to store array only but this shows the difference : 
#!/usr/bin/perl

use strict;
use warnings;

my @coins = ("twenty","thirthy","fourthy");
my $key;
my $value;

my ($index) = grep($coins[$_] eq "fourthy", 0 .. $#coins);
print "\nthe index of 'fourthy' is " . $index . "\n";

my @index2 = grep($_ ne "fourthy", @coins);
print "\nnone 'fourthy' elements are " . join(",",@index2);

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question :
1. why ($index) needs to be written in bracket for the grep to return an appropriate index number?

2. both grep's $_ symbol seems to work differently..is this dependent on the 2nd parameter of grep? one works as a key, another as a value!

3. why can grep's 2nd parameter be either an array or sequence of array index?

In reply to grep usage confusion by adrive

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