具有意外行为的PHP神奇方法

因为

为空

检查变量是否存在，然后检查变量是否为空。如果它不存在（在您的情况下，因为您没有向它传递变量），那么它将返回

true

---

签出文档页面：

请记住，

empty

是一种语言构造，而不是函数，必须处理实际变量（除非您使用的是PHP>=5.5.0）。。。。现在请阅读有关魔法的方法。。。这是有道理的。谢谢谢谢我没有做最基本的事情：查看文档。

<?php

class MyClass{

    private $props;

    public function __constructor(){
        $this->props = array();
    }

    public function __get($field) {
        return $this->props[$field];
    }

    public function __set($field, $value) {
        $this->props[$field] = $value;
    }
}


$myInstance = new MyClass();
$myInstance->a = "Some string";

echo "Property 'a' has value ",$myInstance->a,"<br />"; // First echo
echo "Is property 'a' empty? ",(empty($myInstance->a) ? "Yes, but it shouldn't!" : "No, as expected"); // Second echo
// Output:
// Property 'a' has value Some string
// Is property 'a' empty? Yes, but it shouldn't!


$temp = $myInstance->a;
echo 'Variable $temp has value ',$temp,"<br />";
echo 'Is variable $temp empty? ',(empty($temp) ? "Yes, but it shouldn't!" : "No, as expected");
// Output:
// Variable $temp has value Some string
// Is variable $temp empty? No, as expected

?>