#! /usr/bin/env python
#coding=utf-8
# 获取今天、昨天和明天的日期
# 引入datetime模块
import datetime 
#计算今天的时间
today = datetime.date.today()
#计算昨天的时间 
yesterday = today - datetime.timedelta(days = 1)
#计算明天的时间
tomorrow = today + datetime.timedelta(days = 1) 
#打印这三个时间
print(yesterday, today, tomorrow)

#! /usr/bin/env python
#coding=utf-8
# 计算上一个的时间
#引入datetime,calendar两个模块
import datetime,calendar
 
last_friday = datetime.date.today() 
oneday = datetime.timedelta(days = 1) 
 
while last_friday.weekday() != calendar.FRIDAY: 
 last_friday -= oneday 
 
print(last_friday.strftime('%A, %d-%b-%Y'))

#! /usr/bin/env python
#coding=utf-8
# 借助模运算，可以一次算出需要减去的天数，计算上一个星期五
#同样引入datetime,calendar两个模块
import datetime 
import calendar 
 
today = datetime.date.today() 
target_day = calendar.FRIDAY 
this_day = today.weekday() 
delta_to_target = (this_day - target_day) % 7
last_friday = today - datetime.timedelta(days = delta_to_target) 
 
print(last_friday.strftime("%d-%b-%Y"))

#! /usr/bin/env python
#coding=utf-8
# 获取一个列表中的所有歌曲的播放时间之和 
import datetime 
 
def total_timer(times): 
 td = datetime.timedelta(0) 
 duration = sum([datetime.timedelta(minutes = m, seconds = s) for m, s in times], td) 
 return duration 
 
times1 = [(2, 36), 
   (3, 35), 
   (3, 45), 
   ] 
times2 = [(3, 0), 
   (5, 13), 
   (4, 12), 
   (1, 10), 
   ] 
 
assert total_timer(times1) == datetime.timedelta(0, 596) 
assert total_timer(times2) == datetime.timedelta(0, 815) 
 
print("Tests passed.\n"
  "First test total: %s\n"
  "Second test total: %s" % (total_timer(times1), total_timer(times2)))

#! /usr/bin/env python
#coding=utf-8
# 以需要的时间间隔执行某个命令 
 
import time, os 
 
def re_exe(cmd, inc = 60): 
 while True: 
  os.system(cmd); 
  time.sleep(inc) 
 
re_exe("echo %time%", 5)

#! /usr/bin/env python
#coding=utf-8
#这里需要引入三个模块
import time, os, sched 
 
# 第一个参数确定任务的时间，返回从某个特定的时间到现在经历的秒数 
# 第二个参数以某种人为的方式衡量时间 
schedule = sched.scheduler(time.time, time.sleep) 
 
def perform_command(cmd, inc): 
 os.system(cmd) 
  
def timming_exe(cmd, inc = 60): 
 # enter用来安排某事件的发生时间，从现在起第n秒开始启动 
 schedule.enter(inc, 0, perform_command, (cmd, inc)) 
 # 持续运行，直到计划时间队列变成空为止 
 schedule.run() 
  
 
print("show time after 10 seconds:") 
timming_exe("echo %time%", 10)

#! /usr/bin/env python
#coding=utf-8
import time, os, sched 
 
# 第一个参数确定任务的时间，返回从某个特定的时间到现在经历的秒数 
# 第二个参数以某种人为的方式衡量时间 
schedule = sched.scheduler(time.time, time.sleep) 
 
def perform_command(cmd, inc): 
 # 安排inc秒后再次运行自己，即周期运行 
 schedule.enter(inc, 0, perform_command, (cmd, inc)) 
 os.system(cmd) 
  
def timming_exe(cmd, inc = 60): 
 # enter用来安排某事件的发生时间，从现在起第n秒开始启动 
 schedule.enter(inc, 0, perform_command, (cmd, inc)) 
 # 持续运行，直到计划时间队列变成空为止 
 schedule.run() 
  
 
print("show time after 10 seconds:") 
timming_exe("echo %time%", 10)