如何检查多个键是否等于某个值

像这样：

if (isset ($_POST['id'])) {
        $productid = $_POST['id'];
        $size = $_POST['size'];
        $wasfound = false;
        $i = 0;
        if (!isset ($_SESSION['cart']) || count($_SESSION['cart']) < 1) {
            $_SESSION['cart'] = array (0 => array ("product_id" => $productid, "size" => $size, "quantity" => 1));
        }
        else {
            foreach ($_SESSION['cart'] as $eachitem) {
                $i++;
                while (list ($key, $value) = each ($eachitem)) {
                    if ($key == "product_id" && $value == $productid) {
                        array_splice ($_SESSION['cart'], $i-1, 1, array (array ("product_id" => $productid, "quantity" => $eachitem['quantity'] + 1)));
                        $wasfound = true;
                    }
                    else if ($key == "size" && $value == $size) {
                        //do something
                    }
                }
            }
            if ($wasfound == false) {
                array_push ($_SESSION['cart'], array ("product_id" => $productid, "size" => $size, "quantity" => 1));
            }
        }
        header ("location: cart.php");
        exit;

如果您想做两件单独的事情，可以使用第一个，如果其中一个条件正确，则可以使用第二个。

while (list ($key, $value) = each ($eachitem)) {
    if ($key == "product_id" && $value == $productid) {
        array_splice ($_SESSION['cart'], $i-1, 1, array (array ("product_id" => $productid, "quantity" => $eachitem['quantity'] + 1)));
        $wasfound = true;
    } elseif ($key == "size" && $value == $size) {
        // DO SOMETHING
    }
}
while (list ($key, $value) = each ($eachitem)) {
    if (($key == "product_id" && $value == $productid) || ($key == "size" && $value == $size)) {
        array_splice ($_SESSION['cart'], $i-1, 1, array (array ("product_id" => $productid, "quantity" => $eachitem['quantity'] + 1)));
        $wasfound = true;
    }
}