Or even

for my $need (grep { /^sanj/ } @need) {
    $array1[$incr1++] = $need;
}

#although maybe in that case you would just do the more readable
for my $need (@need) {
    if($need =~ /^sanj/) {
         $array1[$incr1++] = $need;
    }
}
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And to make that warning go away in places you really need the eq there is if(defined $foo && $foo eq 'bar')