空合并运算符，带铸造 [英] Null coalesce operator with casting

问题描述

我已经升级到PHP 7，并开始使用null合并运算符转换诸如此类的

I have upgraded to PHP 7 and started using the null coalesce operator to convert things like

$email = isset($_SESSION['email']) ? $_SESSION['email'] : '';

到

$email = $_SESSION['email'] ?? '';

但是如果我也进行投射，我不知道该怎么做.例如，旧语句的

but I can't figure out how to do this if I am casting as well. For example, the for the old statement

$id = isset($_GET['id']) ? (int) $_GET['id'] : 0;

我会想像

$id = (int) $_GET['id'] ?? 0;

应该可以工作，但是从某种意义上讲，如果未设置$_GET['id']，则$id会解析为0，但我会收到通知

should work, but it doesn't appear to in the sense that, if $_GET['id'] is not set, $id resolves to 0 but I get the Notice

注意:未定义的索引:第2行中test.php中的ID

Notice: Undefined index: id in test.php on line 2

推荐答案

(int)强制转换优先于??运算符，因此请使用方括号:

The (int) cast gets precedence over the ?? operator, so use brackets:

$id = (int) ($_GET['id'] ?? 0);

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