如何在PHP中提取“日期字符串”的“格式字符串”

Question

Date-Time is read from external resource and stored in $dt, And it could be in any valid PHP Date-Time format (valid means date-time is already formated by a string containing letters described here on php.net manual ).

What I need to do is to get format of the date-time string, So after manipulating the date to system needs, I can reformat it to the same string and store it in database. Simply put: do opposite of DateTime::format method

Is there any particular method which extracts 'format string' of a formated date-time? or an available code?

Answer 1

It is not possible, as the formatted dates can not contain enough information. You will have to write some set of regexp to match your formats which are really used as your inputs - one by one.

Answer 2

You could take them all to a unix timestamp and then use date to get a standardised form. Or you could standardise your input in the first place (which is usually the easier option - because error catching is going to be a mare!)

\\$dt your datetime input
$timestring = strtotime($dt);
$datetime = date("H:i:s j M Y", $timestring);

Of course, you might get some funny outputs from strtotime if your inputs are weird.