py3笔记4：datetime常见时间处理方法

#-*-coding:utf-8-*-
"""
@author:百草
@file:getEmail_note.py
@time:2021/09/06
"""
import datetime
# 1. 获取当前时间
now = datetime.datetime.now()
tod = datetime.datetime.today()
print(f"today= {tod}")  # today= 2021-09-07 22:26:30.494616
print(f"now = {now}")  # now = 2021-09-07 22:26:30.494616

now_time =now.time()
print(now_time)  # 22:49:07.616614
print(now.minute)  # 49 分
print(now.hour)    # 小时，22
print(now.second)  # 整数秒，52

# 返回一个time结构
print("time结构：",now.timetuple(), type(now.timetuple()))
# time.struct_time(tm_year=2021, tm_mon=9, tm_mday=7, tm_hour=22, tm_min=31,
#                   tm_sec=32, tm_wday=1, tm_yday=250, tm_isdst=-1) <class 'time.struct_time'>

# 返回一个date结构
print("date结构：", now.date(), type(now.date()))  # date结构： 2021-09-07 <class 'datetime.date'>

# 返回一个time类型
print("time类型：", now.time())  # time类型： 22:33:46.180543

# 返回当前星期几
print("今天星期几(0-周一；6-周日)：", now.weekday())  # 今天星期几(0-周一；6-周日)： 1
# 0-周一；6-周日

# 返回当前星期几
print("今天星期几(1-周一；7-周日):", now.isoweekday())  # 今天星期几(1-周一；7-周日): 2

# ========================================================

# 2. 当前时间添加/减少
time2 = now - datetime.timedelta(hours=1)
#     timedelta(days: float = ..., seconds: float = ..., ,
#               microseconds: float,  # 微秒
#               milliseconds: float,  # 毫秒
#               minutes: float = ..., hours: float = ...,
#               weeks: float = ...)
print(time2)  # 2021-09-06 20:49:52.668491

# 3. 格式化字符串输出
time_string = now.strftime("%Y/%m/%d was a %a")
print(time_string)  # 2021/09/07 was a Tuesday
# %Y 年，如2021(4位);   %y 年，如21，后两位
# %m ,月，如09;  # %M  分，如49
# %d, 日，如07;   %D 日期，如09/07/21 月/日/年(2位)
# %H 时,如22（24小时制度）;%h 月份的英文缩写，如Sep
# %S 秒;  %s 无效
# %A, 星期，如Tuesday； %a ,如Tue

# 4. 字符串转化为时间类型
time3 = "2021/09/07"
time3 = datetime.datetime.strptime(time3,"%Y/%m/%d")
# 第1个参数time_string:字符串类型的时间；
# 第2个参数format:time_string的格式
print(time3, type(time3))  # 2021-09-07 00:00:00  <class 'datetime.datetime'>

# 5. 修改当前时间
time4 = now.replace(year=2020)
print("修改后的时间=", time4)  # 修改后的时间= 2020-09-07 22:38:13.150296
# 参数：year=None, month=None, day=None, hour=None, minute=None, second=None, microsecond=None, tzinfo=True, fold=None

# 6.进行比较运算，返回timedelta类型
past = datetime.datetime(2021, 8, 7, 20, 11, 59)
time5 = now-past
print("比较运算结果：", time5, type(time5))  # 比较运算结果： 31 days, 2:30:59.896544 <class 'datetime.timedelta'>

# ========================================================
# 练习：本月的第1天，本周的第一天
def get_first_day_of_month():
    day = datetime.datetime.now().day  # 今天的日day
    return datetime.datetime.today()-datetime.timedelta(days=day-1)

print(f"获取本月第一天：{get_first_day_of_month()}")

def get_first_day_of_week():
    day = datetime.datetime.now().weekday()  # 周几
    print(day)  # Tueday,阿拉伯数字=1
    return datetime.datetime.now()-datetime.timedelta(days=day)

print(f"获取本周第一天：{get_first_day_of_week()}")