Php 如何检查数组中是否存在值，以及该值是否增加

我有以下代码。我希望

elseif

部分检查

$pId

是否已在数组中，如果已在数组中，我希望增加其

数量和
价格，而不是向数组中添加新的
$pId

我不知道我是否使用了错误的方法，或者我的数组结构是否错误，但我无法让它增加这些值

if (!isset($_SESSION['cart'])) {
    $_SESSION['cart'] = array();
    $_SESSION['cart']['pid'][] = $pid;
    $_SESSION['cart']['pid']['price'] = $price;
    $_SESSION['cart']['pid']['quantity'] = $quantity;
    $_SESSION['cart']['total_price'] = $price;
    $_SESSION['cart']['total_items'] = $quantity;
}elseif(array_key_exists($pid, $_SESSION['cart'])){
    //increase price
    //increase quantity
}else{
    $_SESSION['cart']['pid'][] = $pid;
    $_SESSION['cart']['pid']['price'] = $price;
    $_SESSION['cart']['total_price'] += $price;
    $_SESSION['cart']['total_items'] += $quantity;
}

我在数组中添加了一个额外的维度，因此您可以轻松地选择它

if (!isset($_SESSION['cart'])) {
    $_SESSION['cart'] = array('pid' => array(), 'total_price' => 0, 'total_items' => 0);
    $_SESSION['cart']['pid'][$pid] = array();
    $_SESSION['cart']['pid'][$pid]['price'] = $price;
    $_SESSION['cart']['pid'][$pid]['quantity'] = $quantity;
    $_SESSION['cart']['total_price'] = $price;
    $_SESSION['cart']['total_items'] = $quantity;
}elseif(array_key_exists($pid, $_SESSION['cart']['pid'])){
    $_SESSION['cart']['pid'][$pid]['price'] = 'new price';
    $_SESSION['cart']['pid'][$pid]['quantity'] = 'new quantity';
}else{
    $_SESSION['cart']['pid'][$pid]['price'] = $price;
    $_SESSION['cart']['total_price'] += $price;
    $_SESSION['cart']['total_items'] += $quantity;
}

我不知道
pid
代表什么，但乍一看，它并没有真正的描述性。也许
产品
会是一个更好的键？
@repwhoringpeehaha当前值加上新值。例如
price+=
；