Echo count out within foreach loop

How can I echo out the count of within a foreach loop? I want to change the class of the div below so it's menu-button-1, menu-button-2 etc etc:

    <?php 
$开发者_JAVA技巧pages = get_children(array('orderby' => 'menu_order', 'order' => 'asc'));
foreach($pages as $post) {
setup_postdata($post);
$fields = get_fields();
?>

    <div class="menu-button-(insert counter here)">
        <a href="<?php echo get_page_link( $post->ID ); ?>"><?php echo $post->post_title; ?></a>
    </div>
<?php
}
wp_reset_query();
?>

So I want it to output something like this - <div class="menu-button-1"> then <div class="menu-button-2"> and so on each time it goes through the loop.

    <?php 
$pages = get_children(array('orderby' => 'menu_order', 'order' => 'asc'));
$i=1;
foreach($pages as $post) {
setup_postdata($post);
$fields = get_fields();
?>

    <div class="menu-button-$i">
        <a href="<?php echo get_page_link( $post->ID ); ?>"><?php echo $post->post_title; ?></a>
    </div>
<?php
$i++;
}
wp_reset_query();
?>