WooCommerce Dropdown Product Quantity, including selected quantity in cart. Fully compatible with Min/Max quantities extension

functions.php

<?php
// Place the following code in your theme's functions.php file
// override the quantity input with a dropdown
function woocommerce_quantity_input($data = null) {

global $product;

$defaults = array(
    'input_name' => 'quantity',
    'input_value' => '1',
    'max_value' => apply_filters( 'woocommerce_quantity_input_max', '', $product ),
    'min_value' => apply_filters( 'woocommerce_quantity_input_min', '', $product ),
    'step' => apply_filters( 'woocommerce_quantity_input_step', '1', $product ),
    'style' => apply_filters( 'woocommerce_quantity_style', 'float:left;', $product )
);

$data = wp_parse_args( $data, $defaults );


if ( ! empty( $data['min_value'] ) )
$min = $data['min_value'];
else $min = 1;

if ( ! empty( $data['max_value'] ) )
$max = $data['max_value'];
else $max = 20;

if ( ! empty( $data['step'] ) )
$step = $data['step'];
else $step = 1;

$options = '';

for ( $count = $min; $count <= $max; $count = $count+$step ) {
$selected = $count === $data['input_value'] ? ' selected' : '';
$options .= '<option value="' . $count . '"'.$selected.'>' . $count . '</option>';
}

echo '<div class="quantity_select" style="' . $data['style'] . '"><select name="' . esc_attr( $data['input_name'] ) . '" title="' . _x( 'Qty', 'Product quantity input tooltip', 'woocommerce' ) . '" class="qty">' . $options . '</select></div>';

}
?>