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phpdebuggingdatetimephp-internals

print_r() adds properties to DateTime objects

Consider the following code sample:

$m_oDate = new DateTime('2013-06-12 15:54:25');
print_r($m_oDate);
echo $m_oDate->date;

Since PHP 5.3, this produces (something like) the following output:

DateTime Object
(
    [date] => 2013-06-12 15:54:25
    [timezone_type] => 3
    [timezone] => Europe/Amsterdam
)
2013-06-12 15:54:25

However the following code:

$m_oDate = new DateTime('2013-06-12 15:54:25');
echo $m_oDate->date;

...simply emits an error:

Notice: Undefined property: DateTime::$date in ...

Why does print_r() "add" these properties to the object? Note that they are not defined as part of the DateTime class on the manual page.

Solution

  • There is some magic occurring but it's pretty simple.

    The class DateTime doesn't have a public variable 'date' that you're meant to access. However, as a side effect of how PHP works, there is a variable created when you call print_r or var_dump on that class.

    After that magic happens 'date' is available, but it shouldn't be. You should just use the getTimestamp function to make your code work reliably.