DateTime 对象的严格比较
Strict comparison of DateTime Objects
我正在对对象列表进行严格比较，只是为了识别可能已更改的对象，例如：
if ($oldValue !== $newValue)
在某些情况下 $oldValue 和 $newValue 是 DateTime 个对象。
调试我的应用程序我在比较它们之前得到以下两个值的输出：
DateTime Object
(
[date] => 2017-04-24 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
DateTime Object
(
[date] => 2017-04-24 00:00:00.000000
[timezone_type] => 3
[timezone] => UTC
)
为什么我的 comparison/condition 仍然正确？
比较 PHP 中的对象时，=== 运算符不比较值。 It compares instances。这意味着除非两个对象都指向同一个对象，否则它们并不严格相等。
When using the comparison operator (==), object variables are compared
in a simple manner, namely: Two object instances are equal if they
have the same attributes and values (values are compared with ==), and
are instances of the same class.
When using the identity operator (===), object variables are identical
if and only if they refer to the same instance of the same class.
我正在对对象列表进行严格比较，只是为了识别可能已更改的对象，例如：
if ($oldValue !== $newValue)
在某些情况下 $oldValue 和 $newValue 是 DateTime 个对象。
调试我的应用程序我在比较它们之前得到以下两个值的输出：
DateTime Object ( [date] => 2017-04-24 00:00:00.000000 [timezone_type] => 3 [timezone] => UTC )
DateTime Object ( [date] => 2017-04-24 00:00:00.000000 [timezone_type] => 3 [timezone] => UTC )
为什么我的 comparison/condition 仍然正确？
比较 PHP 中的对象时，=== 运算符不比较值。 It compares instances。这意味着除非两个对象都指向同一个对象，否则它们并不严格相等。
When using the comparison operator (==), object variables are compared in a simple manner, namely: Two object instances are equal if they have the same attributes and values (values are compared with ==), and are instances of the same class.
When using the identity operator (===), object variables are identical if and only if they refer to the same instance of the same class.