HOWTO · Python
Python 如何將字串轉換為時間日期 datetime 格式
本文介紹了 Python 如何將字串轉換成 datetime 物件。
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本教程來介紹 Python 如何將字串 string 轉換為 datetime 物件，隨後列舉出來程式碼例子來實現流行的時間格式的轉化。
datetime.strptime() 將字串轉換為 datetime
在以前的教程中，我們介紹了使用 datetime.strftime() 方法將 datetime 轉化為字串。這裡我們將用 datetime.strptime() 方法來實現逆轉換。兩種方法中的差別 f 和 p 分別對應著 format（格式）和 parse（解析）。
datetime.strptime() 按照給定的 datetime 格式來解析字串，解析成功的話，返回 datetime 物件。
下面的例子是 datetime.strptime() 的簡單使用例子。
from datetime import datetime
datetime.strptime("2018-01-31", "%Y-%m-%d")
它的返回結果是，
datetime.datetime(2018, 1, 31, 0, 0)
The directives of the string format codes are listed here for your reference
| Directive | Meaning | Example |
|---|---|---|
%a |
Weekday as locale’s abbreviated name. | Sun, Mon, …, Sat (en_US);So, Mo, …, Sa (de_DE) |
%A |
Weekday as locale’s full name. | Sunday, Monday, …, Saturday (en_US);Sonntag, Montag, …, Samstag (de_DE) |
%w |
Weekday as a decimal number, where 0 is Sunday and 6 is Saturday. | 0, 1, …, 6 |
%d |
Day of the month as a zero-padded decimal number. | 01, 02, …, 31 |
%b |
Month as locale’s abbreviated name. | Jan, Feb, …, Dec (en_US);Jan, Feb, …, Dez (de_DE) |
%B |
Month as locale’s full name. | January, February, …, December (en_US);Januar, Februar, …, Dezember (de_DE) |
%m |
Month as a zero-padded decimal number. | 01, 02, …, 12 |
%y |
Year without century as a zero-padded decimal number. | 00, 01, …, 99 |
%Y |
Year with century as a decimal number. | 0001, 0002, …, 2013, 2014, …, 9998, 9999 |
%H |
Hour (24-hour clock) as a zero-padded decimal number. | 00, 01, …, 23 |
%I |
Hour (12-hour clock) as a zero-padded decimal number. | 01, 02, …, 12 |
%p |
Locale’s equivalent of either AM or PM. | AM, PM (en_US);am, pm (de_DE) |
%M |
Minute as a zero-padded decimal number. | 00, 01, …, 59 |
%S |
Second as a zero-padded decimal number. | 00, 01, …, 59 |
%f |
Microsecond as a decimal number, zero-padded on the left. | 000000, 000001, …, 999999 |
%z |
UTC offset in the form ±HHMM[SS] (empty string if the object is naive). | (empty), +0000, -0400, +1030 |
%Z |
Time zone name (empty string if the object is naive). | (empty), UTC, EST, CST |
%j |
Day of the year as a zero-padded decimal number. | 001, 002, …, 366 |
%U |
Week number of the year (Sunday as the first day of the week) as a zero padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0. | 00, 01, …, 53 |
%W |
Week number of the year (Monday as the first day of the week) as a decimal number. All days in a new year preceding the first Monday are considered to be in week 0. | 00, 01, …, 53 |
%c |
Locale’s appropriate date and time representation. | Tue Aug 16 21:30:00 1988 (en_US);Di 16 Aug 21:30:00 1988 (de_DE) |
%x |
Locale’s appropriate date representation. | 08/16/88 (None);08/16/1988 (en_US);16.08.1988 (de_DE) |
%X |
Locale’s appropriate time representation. | 21:30:00 (en_US);21:30:00 (de_DE) |
%% |
A literal '%' character. |
% |
datetime.strptime() 舉例
7-May-2013 格式
from datetime import datetime
dateString = "7-May-2018"
dateFormatter = "%u-%b-%Y"
datetime.strptime(dateString, dateFormatter)
輸出：
datetime.datetime(2013, 5, 1, 0, 0)
31/12/2018 格式
from datetime import datetime
dateString = "31/12/2013"
dateFormatter = "%d/%m/%Y"
datetime.strptime(dateString, dateFormatter)
輸出：
datetime.datetime(2013, 12, 31, 0, 0)
Mon, July 16 2018 格式
from datetime import datetime
dateString = "31/12/2013"
dateFormatter = "%d/%m/%Y"
datetime.strptime(dateString, dateFormatter)
輸出：
datetime.datetime(2018, 7, 16, 0, 0)
Monday, July 16, 2018 20:01:56 格式
from datetime import datetime
dateString = "Monday, July 16, 2018 20:01:56"
dateFormatter = "%A, %B %d, %Y %H:%M:%S"
datetime.strptime(dateString, dateFormatter)
輸出：
datetime.datetime(2018, 7, 16, 20, 1, 56)
