time和datetime模块

Posted 2020-09-18 Python之旅

time.altzone  #返回与UTC时间的时间差

time.time()  #时间戳，1970年到现在的时间，以秒计算，时间戳可以对时间进行运算。

 

time.asctime()  #返回时间格式"Sun May 14 13:40:11 2017"，不加对象默认为当前时间，如：time.asctime(time.localtime(time.time()+3600*3))，当前时间往后推迟3小时，这种格式一般美国人在用

time.ctime() #返回当前时间\'Sun May 14 14:33:00 2017\'

 

time.localtime() #返回本地时间 的struct time对象格式,time.struct_time(tm_year=2017, tm_mon=5, tm_mday=14, tm_hour=14, tm_min=3, tm_sec=0, tm_wday=6, tm_yday=134, tm_isdst=0)，struct time为一个元组，只能读

　　　　　　　　可以进行时间运算，用时间戳的方式。如

　　　　　　　　time.localtime(time.time()+3600*3) #往后推迟3小时

 

time.gmtime() #返回UTC时间的struct time对象格式，time.struct_time(tm_year=2017, tm_mon=5, tm_mday=14, tm_hour=6, tm_min=3, tm_sec=0, tm_wday=6, tm_yday=134, tm_isdst=0)

 

time.strptime(string,format)#把字符串的时间格式 格式化输出一个struct_time

time.strftime(format，struct_time)  #把struct_time对象格式化输出一个字符串的时间格式

如：

time.strptime(\'2017-5-1 23:59:59\',\'%Y-%m-%d %H:%M:%S\') ->time.struct_time(tm_year=2017, tm_mon=5, tm_mday=1, tm_hour=23, tm_min=59, tm_sec=59, tm_wday=0, tm_yday=121, tm_isdst=-1)

 

time.mktime() #将时间对象转成时间戳

 

 

#日期字符串转成时间戳

如：把一个字符串格式为\'2017-5-1 23:59:59\'转换成时间戳

t = time.strptime(\'2017-5-1 23:59:59\',\'%Y-%m-%d %H:%M:%S\')   #先把字符串转为为struct-time格式

print(time.mktime(t))  ->1493654399.0                                       #再用mktime函数转换为时间戳

 

#将时间戳转换为字符串格式

如：

t = time.strptime(\'2017-5-1 23:59:59\',\'%Y-%m-%d %H:%M:%S\')

t1_stamp = time.mktime(t)                                                    #得到时间戳

t2 = time.localtime(t1_stamp)　　　　　　　　　　 #时间戳转换为struct-time格式

t3 = time.strftime(\'%Y-%m-%d %H-%M-%S\',t2)  #转换为想要的时间字符串格式

print(t3) ->2017-05-01 23-59-59

 

 

时间格式

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.

 

 

 

datetime模块

时间运算

import datetime
print(datetime.datetime.now()) #返回当前时间2017-05-14 15:50:19.881892
print(datetime.date.fromtimestamp(time.time()) )  # 时间戳直接转成日期格式 2016-08-19，好像没什么用
print(datetime.datetime.now() )
print(datetime.datetime.now() + datetime.timedelta(3)) #当前时间+3天
print(datetime.datetime.now() + datetime.timedelta(-3)) #当前时间-3天
print(datetime.datetime.now() + datetime.timedelta(hours=3)) #当前时间+3小时
print(datetime.datetime.now() + datetime.timedelta(minutes=30)) #当前时间+30分

c_time  = datetime.datetime.now()
print(c_time.replace(minute=3,hour=2)) #时间替换