`$_` variable giving incorrect output

Question

If I do

my @answer = qw(java python perl c);
foreach (@answer){
          print "[$_]\n";
}

then it will print

[java]
[python]
[perl]
[c]

But, if I add $answer before [$_]:

my @answer = qw(java python perl c);
foreach (@answer){
       print "$answer[$_]\n";
}

then it will print

java java java java

Why is that?

Answer 1

Each element in the loop is put into $_. When you say $answer[$_], you're asking for the array element $answer['java'], $answer['python'], and so on. These strings turn into 0 in numeric context, and therefore what you get is $answer[0], which is java.