Php wordpress/woocommerce-自定义字段的总和

我在woocommerce中添加了一个输入字段（与每个订单链接）。我可以使用以下代码完美地显示该字段的每个值：

function MY_COLUMNS_VALUES_FUNCTION( $column ) {
    global $post;
    $order = new WC_Order( $post->ID );
    $items = $order->get_items();

    //start editing, I was saving my fields for the orders as custom post meta
    //if you did the same, follow this code
    if ( $column == 'authors_income' ) {
        foreach ( $items as $item ) {

            echo $item['MY-FIELD-NAME'];

        }
    }

---

但是，如何将该字段的所有值求和，并对其进行回显/打印呢

只需将当前值添加到变量，并在循环后回显结果

if ( $column == 'authors_income' ) {
   $totalIncome = 0;
    foreach ( $items as $item ) {

        echo $item['MY-FIELD-NAME'];
        $totalIncome = $totalIncome + $item['MY-FIELD-NAME'];

    }
    echo $totalIncome;
}

---

hm.In返回0。而这个值应该在45左右。