Problem with php special character

Question

I have this script that separates a string by character.

<?php
    $key = "VÔMITOS";
      for( $i=0; $i < $n_caracteres ; $i++ ){
        print $key[$i]."\n";
      }
    ?>

And it returns the following error: V M I T O.

I’ve used the following codes

In HTML

<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 

In PHP

ini_set('default_charset','UTF-8');
header( 'Content-Type: text/html; charset=utf-8' );

Someone would have a solution.