Python3 Date and Time

Python programs can handle dates and times in many ways, and converting date formats is a common feature.

Python provides a time and calendar module that can be used to format dates and times.

Time intervals are floating-point decimals in seconds.

Each timestamp is expressed as how long it has been since midnight (epoch) on January 1, 1970.

There are many functions in Python's time module that can convert common date formats. For example, the function time.time() is used to get the current timestamp, as in the example below:

The output of the above example is:

当前时间戳为: 1459996086.7115328

Timestamp units are most suitable for date arithmetic. However, dates before 1970 cannot be represented this way. Dates too far in the future are also not possible, as UNIX and Windows only support up to 2038.

What is a time tuple?

Many Python functions process time using a tuple of 9 groups of numbers:

The above is the struct_time tuple. This structure has the following attributes:

Get current time

To convert from a timestamp returning a floating-point number to a time tuple, just pass the floating-point number to functions like localtime.

#!/usr/bin/python3

import time

localtime = time.localtime(time.time())
print ("本地时间为 :", localtime)

The output of the above example is:

本地时间为 : time.struct_time(tm_year=2016, tm_mon=4, tm_mday=7, tm_hour=10, tm_min=28, tm_sec=49, tm_wday=3, tm_yday=98, tm_isdst=0)

Get formatted time

You can choose various formats according to your needs, but the simplest function for obtaining a readable time pattern is asctime():

#!/usr/bin/python3

import time

localtime = time.asctime( time.localtime(time.time()) )
print ("本地时间为 :", localtime)

The output of the above example is:

本地时间为 : Thu Apr  7 10:29:13 2016

Format dates

We can use the strftime method of the time module to format dates:

time.strftime(format[, t])

The output of the above example is:

2016-04-07 10:29:46
Thu Apr 07 10:29:46 2016
1459175064.0

Time and date formatting symbols in Python:

• %y Two-digit year representation (00-99)
• %Y Four-digit year representation (000-9999)
• %m Month (01-12)
• %d Day of the month (0-31)
• %H Hour in 24-hour format (0-23)
• %I Hour in 12-hour format (01-12)
• %M Minutes (00-59)
• %S Seconds (00-59)
• %a Local abbreviated weekday name
• %A Local full weekday name
• %b Local abbreviated month name
• %B Local full month name
• %c Local appropriate date and time representation
• %j Day of the year (001-366)
• %p Local equivalent of A.M. or P.M.
• %U Week number of the year (00-53), Sunday is the start of the week
• %w Weekday (0-6), Sunday is the start of the week
• %W Week number of the year (00-53), Monday is the start of the week
• %x Local appropriate date representation
• %X Local appropriate time representation
• %Z Name of the current time zone
• %% The percent sign itself

Get calendar for a month

The Calendar module has a wide range of methods for handling yearly and monthly calendars, for example printing a month's calendar:

The output of the above example is:

以下输出2016年1月份的日历:
    January 2016
Mo Tu We Th Fr Sa Su
             1  2  3
 4  5  6  7  8  9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28 29 30 31

Time Module

The Time module contains the following built-in functions, both for time processing and for converting time formats:

>>> import time
>>> print ("time.altzone %d " % time.altzone)
time.altzone -28800 

>>> import time
>>> t = time.localtime()
>>> print ("time.asctime(t): %s " % time.asctime(t))
time.asctime(t): Thu Apr  7 10:36:20 2016 

time.perf_counter()  # 返回系统运行时间
time.process_time()  # 返回进程运行时间

>>> import time
>>> print ("time.ctime() : %s" % time.ctime())
time.ctime() : Thu Apr  7 10:51:58 2016

>>> import time
>>> print ("gmtime :", time.gmtime(1455508609.34375))
gmtime : time.struct_time(tm_year=2016, tm_mon=2, tm_mday=15, tm_hour=3, tm_min=56, tm_sec=49, tm_wday=0, tm_yday=46, tm_isdst=0)

>>> import time
>>> print ("localtime(): ", time.localtime(1455508609.34375))
localtime():  time.struct_time(tm_year=2016, tm_mon=2, tm_mday=15, tm_hour=11, tm_min=56, tm_sec=49, tm_wday=0, tm_yday=46, tm_isdst=0)

#!/usr/bin/python3
import time

print ("Start : %s" % time.ctime())
time.sleep( 5 )
print ("End : %s" % time.ctime())

>>> import time
>>> print (time.strftime("%Y-%m-%d %H:%M:%S", time.localtime()))
2016-04-07 11:18:05

>>> import time
>>> struct_time = time.strptime("30 Nov 00", "%d %b %y")
>>> print ("返回元组: ", struct_time)
返回元组:  time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1)

>>> import time
>>> print(time.time())
1459999336.1963577

The Time module contains the following 2 very important attributes:

Calendar Module

The functions in this module are all calendar-related, such as printing a character calendar for a month.

Monday is the default first day of the week, and Sunday is the default last day. To change the setting, call the calendar.setfirstweekday() function. The module includes the following built-in functions:

>>> import calendar
>>> print(calendar.isleap(2000))
True
>>> print(calendar.isleap(1900))
False

>>> import calendar
>>> calendar.monthrange(2014, 11)
(5, 30)

Other related modules and functions

In Python, other modules for handling dates and times include:

• time module
• datetime module