python获取日期加减之后的日期

Posted 2020-10-16

python语言中的datetime模块可以利用其中的方法获取不同的日期，比如获取当前日期、明天、昨天、上个月、下个月和明年。下面利用几个实例说明这些日期的获取方法，操作如下：

 

 

第一步，利用datetime模块获取当前日期
datetime.date.today();
如下图所示：

 

 

 

第二步，获取当前日期前一天日期，利用当前日期减去一天，如下图所示：

 

 

 

第三步，获取当前日期后一天日期，利用当前日期加上一天，如下图所示：

 

 

 

第四步，获取当前日期下一个月日期，利用当前日期加上30天，如下图所示：

 

 

 

第五步，获取当前日期上一个月的日期，利用当前日期减去30天，如下图所示：

 

 

第六步，获取当前日期返回明年今天的日期，利用当前日期加上365天，如下图所示：

 

 

 

• python获取前后N天或前后N个月的日期

  1 # -*- coding: utf-8 -*-
  2 
  3 #-----------------------------------------------------------------------------------
  4 import datetime
  5 #获取366天前的日期
  6 day=(datetime.date.today() - datetime.timedelta(days=366)).strftime(‘%Y-%m-%d‘)
  7 print(day)
  8 #获取366天后的日期
  9 day=(datetime.date.today() + datetime.timedelta(days=366)).strftime(‘%Y-%m-%d‘)
 10 print(day)
 11 #-----------------------------------------------------------------------------------
 12 
 13 ‘‘‘获取当前日期前后N天或N月的日期‘‘‘
 14 
 15 from time import strftime, localtime
 16 from datetime import timedelta, date
 17 import calendar
 18 
 19 
 20 year = strftime("%Y", localtime())
 21 mon = strftime("%m", localtime())
 22 day = strftime("%d", localtime())
 23 hour = strftime("%H", localtime())
 24 min = strftime("%M", localtime())
 25 sec = strftime("%S", localtime())
 26 
 27 
 28 def today():
 29     ‘‘‘‘‘
 30     get today,date format="YYYY-MM-DD"
 31     ‘‘‘‘‘
 32     return date.today()
 33 
 34 def todaystr():
 35     ‘‘‘
 36     get date string, date format="YYYYMMDD"
 37     ‘‘‘
 38     return year + mon + day
 39 
 40 def datetime():
 41     ‘‘‘‘‘
 42     get datetime,format="YYYY-MM-DD HH:MM:SS"
 43     ‘‘‘
 44     return strftime("%Y-%m-%d %H:%M:%S", localtime())
 45 
 46 def datetimestr():
 47     ‘‘‘‘‘
 48     get datetime string
 49     date format="YYYYMMDDHHMMSS"
 50     ‘‘‘
 51     return year + mon + day + hour + min + sec
 52 
 53 def get_day_of_day(n=0):
 54     ‘‘‘‘‘
 55     if n>=0,date is larger than today
 56     if n<0,date is less than today
 57     date format = "YYYY-MM-DD"
 58     ‘‘‘
 59     if (n < 0):
 60         n = abs(n)
 61         return date.today() - timedelta(days=n)
 62     else:
 63         return date.today() + timedelta(days=n)
 64 
 65 def get_days_of_month(year, mon):
 66     ‘‘‘‘‘
 67     get days of month
 68     ‘‘‘
 69     return calendar.monthrange(year, mon)[1]
 70 
 71 def get_firstday_of_month(year, mon):
 72     ‘‘‘‘‘
 73     get the first day of month
 74     date format = "YYYY-MM-DD"
 75     ‘‘‘
 76     days = "01"
 77     if (int(mon) < 10):
 78         mon = "0" + str(int(mon))
 79     arr = (year, mon, days)
 80     return "-".join("%s" % i for i in arr)
 81 
 82 def get_lastday_of_month(year, mon):
 83     ‘‘‘‘‘
 84     get the last day of month
 85     date format = "YYYY-MM-DD"
 86     ‘‘‘
 87     days = calendar.monthrange(year, mon)[1]
 88     mon = addzero(mon)
 89     arr = (year, mon, days)
 90     return "-".join("%s" % i for i in arr)
 91 
 92 def get_firstday_month(n=0):
 93     ‘‘‘‘‘
 94     get the first day of month from today
 95     n is how many months
 96     ‘‘‘
 97     (y, m, d) = getyearandmonth(n)
 98     d = "01"
 99     arr = (y, m, d)
100     return "-".join("%s" % i for i in arr)
101 
102 def get_lastday_month(n=0):
103     ‘‘‘‘‘
104     get the last day of month from today
105     n is how many months
106     ‘‘‘
107     return "-".join("%s" % i for i in getyearandmonth(n))
108 
109 def getyearandmonth(n=0):
110     ‘‘‘‘‘
111     get the year,month,days from today
112     befor or after n months
113     ‘‘‘
114     thisyear = int(year)
115     thismon = int(mon)
116     totalmon = thismon + n
117     if (n >= 0):
118         if (totalmon <= 12):
119             days = str(get_days_of_month(thisyear, totalmon))
120             totalmon = addzero(totalmon)
121             return (year, totalmon, days)
122         else:
123             i = totalmon / 12
124             j = totalmon % 12
125             if (j == 0):
126                 i -= 1
127                 j = 12
128             thisyear += i
129             days = str(get_days_of_month(thisyear, j))
130             j = addzero(j)
131             return (str(thisyear), str(j), days)
132     else:
133         if ((totalmon > 0) and (totalmon < 12)):
134             days = str(get_days_of_month(thisyear, totalmon))
135             totalmon = addzero(totalmon)
136             return (year, totalmon, days)
137         else:
138             i = totalmon / 12
139             j = totalmon % 12
140             if (j == 0):
141                 i -= 1
142                 j = 12
143             thisyear += i
144             days = str(get_days_of_month(thisyear, j))
145             j = addzero(j)
146             return (str(thisyear), str(j), days)
147 
148 def addzero(n):
149     ‘‘‘‘‘
150     add 0 before 0-9
151     return 01-09
152     ‘‘‘
153     nabs = abs(int(n))
154     if (nabs < 10):
155         return "0" + str(nabs)
156     else:
157         return nabs
158 
159 def get_today_month(n=0):
160     ‘‘‘‘‘
161     获取当前日期前后N月的日期
162     if n>0, 获取当前日期前N月的日期
163     if n<0, 获取当前日期后N月的日期
164     date format = "YYYY-MM-DD"
165     ‘‘‘
166     (y, m, d) = getyearandmonth(n)
167     arr = (y, m, d)
168     if (int(day) < int(d)):
169         arr = (y, m, day)
170     return "-".join("%s" % i for i in arr)
171 
172 
173 if __name__ == "__main__":
174     print today()#获取当前日期，2017-12-02
175     print todaystr()#20171202
176     print datetime()#2017-12-02 16:37:19
177     print datetimestr()#20171202163719
178     print get_day_of_day(20)#获取20天后的日期，2017-12-22
179     print get_day_of_day(-3)#获取3天前的日期，2017-11-29
180     print get_today_month(-3)#获取3个月前的日期，  2017-09-02
181     print get_today_month(3)# 获取3个月后的日期， 2018-03-02
182     print get_today_month(19)# 获取19个月后的日期，2019-07-02