在php中进行求和时如何处理空值

我有以下数据，我试图对总票价进行汇总，但php不断抛出此错误

警告：在..

$read_one_vehicle_response = '
                            {
                                "response_code": 0,
                                "response_message": "Request processed successfully",
                                "id": "1",
                                "ticket": [
                                    {
                                        "id": "1",
                                        "total_fare": "1000",
                                        "status": "Paid"
                                    },
                                    {
                                        "id": "2",
                                        "total_fare": "80",
                                        "status": "Paid"
                                    },
                                    {
                                        "id": null,
                                        "total_fare": null,
                                        "status": null
                                    }
                                ],
                                "created": "2020-09-12 15:42:29",
                                "modified": "2020-09-12 20:42:29",
                                "status": "Active"
                            }';


$income = "";

foreach (json_decode($read_one_vehicle_response, true)["ticket"] as $ticket) {

    if (is_numeric($ticket{"total_fare"})) {
       $total_fare = $ticket{"total_fare"};
    }
    else {
        $total_fare = 0.00;
    }
    $income += $total_fare;
}

echo "Total: $income";

---

我已经尝试了上面的方法，它正确地将数字相加，但仍然不断抛出错误。处理此错误的正确方法是什么？I

在do（+）之前转换为float或int类型。尝试：

如果您的数据不能转换为float，它将是0

使用PHP的另一种方法：

---

更多信息和讨论请参见SO about

您正在添加字符串值，并将其转换为浮点值

$income = floatval(0);

foreach (json_decode($read_one_vehicle_response, true)["ticket"] as $ticket) {

    if (is_numeric($ticket{"total_fare"})) {
       $total_fare = floatval($ticket{"total_fare"});
    }
    else {
        $total_fare = 0.00;
    }
    $income += $total_fare;
}

echo "Total: $income";

你可以直接做,

$income = 0;

foreach (json_decode($read_one_vehicle_response, true)["ticket"] as $ticket) {
    $total_fare = (float) $ticket{"total_fare"};

    $income += $total_fare;
}

echo "Total: $income";

---

总票价为10英镑

$income = floatval(0);

foreach (json_decode($read_one_vehicle_response, true)["ticket"] as $ticket) {

    if (is_numeric($ticket{"total_fare"})) {
       $total_fare = floatval($ticket{"total_fare"});
    }
    else {
        $total_fare = 0.00;
    }
    $income += $total_fare;
}

echo "Total: $income";

$income = 0;

foreach (json_decode($read_one_vehicle_response, true)["ticket"] as $ticket) {
    $total_fare = (float) $ticket{"total_fare"};

    $income += $total_fare;
}

echo "Total: $income";