重置foreach循环内的计数器

Question

I am trying to create a simple foreach loop that will group every 16 records in the array. I have also another counter ($s) which I need to be reseted after 4.

Here is my code

$a = array(
  'book-1' => 'Book Title 1',
  'book-2' => 'Book Title 2',
  'book-3' => 'Book Title 3',
  'book-4' => 'Book Title 4',
  'book-5' => 'Book Title 5',
  'book-6' => 'Book Title 6',
  'book-7' => 'Book Title 7',
  'book-8' => 'Book Title 8',
  'book-9' => 'Book Title 9'
);

$i = 1;
$bookshelf = 1;
$s=0;
foreach ( $a as $k => $v ) 
{

    if ($i == 9 || $i == 1)
    {  
      echo '<div id="bookshelf-'.$bookshelf.'"></div>';
      $bookshelf++;
    }


    if ($i%4 == 1)
    {  
      echo '<div class="bookshelf-bottom">';
    }

    if ($i > 5)
    {  
      $s=0;
    }

    $s++;

    echo '<div class="book-frame-'.$s.'">'.$v.'</div>';

    if ($i%4 == 0)
    {
      echo '</div>';
    }

    $i++;
}
if ($i%4 != 1) echo '</div>';

What I am trying to export is :

<div id="bookshelf-1" class="bookshelf-top"></div>

<div class="bookshelf-bottom">
<div class="book-frame-1">Book Title 1</div>
<div class="book-frame-2">Book Title 2</div>
<div class="book-frame-3">Book Title 3</div>
<div class="book-frame-4">Book Title 4</div>
</div>

<div class="bookshelf-bottom">
<div class="book-frame-1">Book Title 5</div>
<div class="book-frame-2">Book Title 6</div>
<div class="book-frame-3">Book Title 7</div>
<div class="book-frame-4">Book Title 8</div>
</div>

<div class="bookshelf-bottom">
<div class="book-frame-1">Book Title 9</div>
</div>

Answer 1

Have a look

<?php
$a = array(
    'book-1' => 'Book Title 1',
    'book-2' => 'Book Title 2',
    'book-3' => 'Book Title 3',
    'book-4' => 'Book Title 4',
    'book-5' => 'Book Title 5',
    'book-6' => 'Book Title 6',
    'book-7' => 'Book Title 7',
    'book-8' => 'Book Title 8',
    'book-9' => 'Book Title 9'
);

$i = 1;
$bookshelf = 1;
$s=0;
foreach ( $a as $k => $v ) {
    $s++;
    if ($i == 9 || $i == 1) {
        if($i == 1)
            echo '<div id="bookshelf-'.$bookshelf.'" class="bookshelf-top"></div>';
        else
            echo '<div id="bookshelf-'.$bookshelf.'"></div>';
      $bookshelf++;
    }
    if($s == 1)
        echo '<div class="bookshelf-bottom">';
    echo '<div class="book-frame-'.$s.'">'.$v.'</div>';
    if($s == 4) {
        echo '</div>';
        $s = 0;
    }
    $i++;
}
?>