dt = datetime.datetime(2019,6,10)
print(type(dt)) 
print(dt.today()) 
print(dt.now()) 
print(dt.utcnow()) 
print(dt.fromtimestamp(time.time()))
print(dt)

t1 = datetime.datetime.now()
print(t1.strftime("%Y{a}%m{a}%d{b}%H{c}%M{c}%S".format(a="/",b=" ",c=":"))) 
t2 =datetime.timedelta(hours=1,days=2,minutes=1,seconds=2) 
print((t1+t2).strftime("%Y{a}%m{a}%d{b}%H{c}%M{c}%S".format(a="/",b=" ",c=":")))

c=''' 
sum= [] 
for i in range(1000): 
  sum.append(i) 
''' 
#利用timeit调用代码，执行100000次，查看运行时间
t4 = timeit.timeit(stmt = "[i for i in range(1000)]",number=100000) 
#测试代码c执行100000次的运行结果 
t5 = timeit.timeit(stmt=c,number=100000) 
print(t4) 
print(t5)