PHP中的DateTime构造函数 [英] DateTime constructor in php

问题描述

我已经对php的 DateTime 类进行了一些实验。在文档中，他们建议了给定DateTime类对象的语法。

I have done a little experiment on php's DateTime class. In the documentation they have suggested the syntax for creating the object of DateTime class as given.

面向对象的样式：

public DateTime::__construct() ( [ string $time = "now" [, DateTimeZone $timezone = NULL ]] )

程序样式：

DateTime date_create ( [ string $time = "now" [, DateTimeZone $timezone = NULL ]] )

返回新的DateTime对象。

Returns new DateTime object.

这里是他们指定为强制性的第一个参数，如日期和时间格式部分。否则，在使用$ timezone参数时，我们必须在此处传递 NULL 来获取当前时间。

Here the first argument they have specified as mandatory, as a date/time string as specified in Date and Time Formats section. Or we have to pass NULL here to obtain the current time when using the $timezone parameter.

但是我的问题是是当我给出以下代码时：

But my problem is when I am giving following code:

date_default_timezone_set('America/Los_Angeles');
$d_ob = new DateTime('x');
echo $d_ob->format('Y-m-d');

应该会生成异常，但它会像-

It's supposed to generate exception, but it's echoing the current date time like -

2013-09-29

我不明白这一点，它是如何工作的？

I am not getting the point, how it's working?

推荐答案

显然，这不是错误，它是预期的 ，但没有记录的行为' ^{查看对错误报告的评论} 。所有单个字母（ j除外）都代表军事时区，请参阅一些代码来演示这一点。

Apparently, this is not a bug, it is 'expected, but undocumented behaviour'^{See the comments to the bug report}. All single letters (except for 'j') represent military timezones, see some code to demonstrate this.

有更多信息此处。

来自 RFC822

军事标准在每个区域使用一个字符。 Z是世界标准时间。 A表示提前一小时， M表示提前十二小时； N是一小时后， Y是十二小时后。

The military standard uses a single character for each zone. "Z" is Universal Time. "A" indicates one hour earlier, and "M" indicates 12 hours earlier; "N" is one hour later, and "Y" is 12 hours later. The letter "J" is not used.

所以回答您的问题

我不明白这一点，它是如何工作的？

I am not getting the point, how it's working?

当DateTime :: __ construct（）时传递了一个不是有效时间字符串的单一值，它假定第一个参数已被省略，并尝试将字符串解析为时区。正如RFC解释的那样， x是有效的时区，因此您将获得位于时区 X中的DateTime实例。

When DateTime::__construct() is passed a single value that is not a valid time string it assumes that the first parameter has been omitted and tries to parse the string as a time zone. As the RFC explains, 'x' is a valid timezone, so you will get a DateTime instance that is in timezone 'X'.

我应该提到，尽管构造函数的\DateTime识别这些单个字母区域，\DateTimeZone的构造函数不会！

I should mention that although the constructor of \DateTime recognises these single letter zones, the constructor of \DateTimeZone does not!

我希望能帮上忙。

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