【个人笔记】
(1) 区分:strptime、strftime
a="04/12/2014 06:08:55"
b = datetime.datetime.strptime(a,"%d/%m/%Y %H:%M:%S") # 将字符串a转化为datetime,用的是strptime
c = datetime.datetime.strftime(b,'%Y-%m-%d %H:%M:%S') # 将datetime b格式化 ,用的是strftime
(2)认识<class 'datetime.timedelta'>
e=b-datetime.datetime.now() # 时间减法
print(type(e), e) # <class 'datetime.timedelta'> 1554 days, 16:00:33.813869
print(e.days, e.seconds, e.microseconds) # 1554 57944 703557
说明:class datetime.timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]]),内部只存储days,seconds,microseconds,
(3)datetime与时间戳的相互转化
import datetime, time
def unix_time():
#将python的datetime转换为unix时间戳
dtime = datetime.datetime.now()
un_time = time.mktime(dtime.timetuple())
print un_time #1509636609.0
#将unix时间戳转换为python 的datetime
unix_ts = 1509636585.0
times = datetime.datetime.fromtimestamp(unix_ts)
print times #2017-11-02 23:29:45
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在python中,日期类型date和日期时间类型dateTime是不能比较的。
(1)如果要比较,可以将dateTime转换为date,date不能直接转换为dateTime
import datetime
dateTime_p = datetime.datetime.now()
date_p = dateTime_p.date()
print(dateTime_p) #2019-01-30 15:17:46.573139
print(date_p) #2019-01-30
(2)日期类型date转换为字符串str
#!/usr/bin/env python3
import datetime
date_p = datetime.datetime.now().date()
str_p = str(date_p)
print(date_p,type(date_p)) #2019-01-30 <class 'datetime.date'>
print(str_p,type(str_p)) #2019-01-30 <class 'str'>
(3)字符串类型str转换为dateTime类型
import datetime
str_p = '2019-01-30 15:29:08'
dateTime_p = datetime.datetime.strptime(str_p,'%Y-%m-%d %H:%M:%S')
print(dateTime_p) # 2019-01-30 15:29:08
print(now.strftime('%a, %b %d %H:%M'))
Mon, May 08 20:22
%a,星期几,缩写
%b,月份,缩写
%d,第几日,罗马数字
%Y-%m-%d %H:%M:%S,年-月-日 时-分-秒,罗马数字
(4)dateTime类型转为str类型
这个地方我也不太理解,为什么指定格式无效
import datetime
dateTime_p = datetime.datetime.now()
str_p = datetime.datetime.strftime(dateTime_p,'%Y-%m-%d')
print(dateTime_p) # 2019-01-30 15:36:19.415157
(5)字符串类型str转换为date类型
#!/usr/bin/env python3
import datetime
str_p = '2019-01-30'
date_p = datetime.datetime.strptime(str_p,'%Y-%m-%d').date()
print(date_p,type(date_p)) # 2019-01-30 <class 'datetime.date'>
另外dateTime类型和date类型可以直接做加1减1这种操作
#!/usr/bin/env python3
import datetime
# today = datetime.datetime.today()
today = datetime.datetime.today().date()
yestoday = today + datetime.timedelta(days=-1)
tomorrow = today + datetime.timedelta(days=1)
print(today) # 2019-01-30
print(yestoday)# 2019-01-29
print(tomorrow)# 2019-01-31