Python3 time库函数

更多详细time库函数参考 https://docs.python.org/3/library/time.html?highlight=strftime#time

形式：

import time
time.()    #下面即将介绍各种()函数

一、时间获取：

1.time():获取当前计算机内部时间，返回浮点数

>>> time.time()
1524146321.7763612  #看不懂的时间表示。。。

2.ctime()：以易读方式获得当前时间，返回字符串

>>> time.ctime()
'Thu Apr 19 21:59:34 2018'   #星期四 2018-4-19 21:59:34

3.gmtime()：获取当前时间，返回计算机可处理的时间格式， 以UTC的时间计

>>> time.gmtime()
time.struct_time(tm_year=2018, tm_mon=4, tm_mday=19, tm_hour=14, tm_min=1, tm_sec=8, tm_wday=3, tm_yday=109, tm_isdst=0) #不知为什么，这个时间有误。。。

4.localtime():获取计算机当前时间，以当地时间计

>>> time.localtime()
time.struct_time(tm_year=2018, tm_mon=4, tm_mday=20, tm_hour=10, tm_min=12, tm_sec=38, tm_wday=4, tm_yday=110, tm_isdst=0)

二、时间格式化：

1.strftime(tpl,ts)：tpl是格式化模板字符串，用来定义输出效果，ts是时间变量

Directive	Meaning	Notes
%a	Locale’s abbreviated weekday name.
%A	Locale’s full weekday name.
%b	Locale’s abbreviated month name.
%B	Locale’s full month name.
%c	Locale’s appropriate date and time representation.
%d	Day of the month as a decimal number [01,31].
%H	Hour (24-hour clock) as a decimal number [00,23].
%I	Hour (12-hour clock) as a decimal number [01,12].
%j	Day of the year as a decimal number [001,366].
%m	Month as a decimal number [01,12].
%M	Minute as a decimal number [00,59].
%p	Locale’s equivalent of either AM or PM.	(1)
%S	Second as a decimal number [00,61].	(2)
%U	Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.	(3)
%w	Weekday as a decimal number [0(Sunday),6].
%W	Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.	(3)
%x	Locale’s appropriate date representation.
%X	Locale’s appropriate time representation.
%y	Year without century as a decimal number [00,99].
%Y	Year with century as a decimal number.
%z	Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59].
%Z	Time zone name (no characters if no time zone exists).
%%	A literal '%' character.

>>> time.strftime('%Y-%m-%d %H:%M:%S',time.localtime())
'2018-04-20 10:34:57'

2.strptime(str,tpl):str是字符串形式的时间值，tpl是格式化模板字符串，定义输出效果

>>> time.strptime('2018-4-19 22:14:15','%Y-%m-%d %H:%M:%S')
time.struct_time(tm_year=2018, tm_mon=4, tm_mday=19, tm_hour=22, tm_min=14, tm_sec=15, tm_wday=3, tm_yday=109, tm_isdst=-1)

三、程序计时：

1.sleep(s)：休眠时间，以秒为单位，可以是浮点数，即等待s秒

2.perf_counter()：返回一个CPU级别的精确时间计数，单位为秒，通过连续求差值可获得程序执行时间

>>> start=time.perf_counter()
>>> end=time.perf_counter()
>>> end-start
10.702251718395534