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我在https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Console/Output/Output.php中看到过这段代码第 40 行他们正在使用 ?int。
public function __construct(?int $verbosity = self::VERBOSITY_NORMAL, bool $decorated = false, OutputFormatterInterface $formatter = null)
{
$this->verbosity = null === $verbosity ? self::VERBOSITY_NORMAL : $verbosity;
$this->formatter = $formatter ?: new OutputFormatter();
$this->formatter->setDecorated($decorated);
}
最佳答案
它称为可空类型。
将 ?int 定义为 int 或 null。
Type declarations for parameters and return values can now be marked as nullable by prefixing the type name with a question mark. This signifies that as well as the specified type, NULL can be passed as an argument, or returned as a value, respectively.
示例:
function nullOrInt(?int $arg){
var_dump($arg);
}
nullOrInt(100);
nullOrInt(null);
函数 nullOrInt 将接受 null 和 int。
关于php - 类型声明前的问号(？)在php(？int)中意味着什么，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49404191/