在Python中，通常有這幾種方式來表示時間：

• 時間戳(timestamp)：通常來說，時間戳表示的是從1970年1月1日00:00:00開始按秒計算的偏移量。我們執行“type(time.time())”，返回的是float型別。
• 格式化的時間字串(Format String)
• 結構化的時間(struct_time)：struct_time元組共有9個元素共九個元素:(年，月，日，時，分，秒，一年中第幾周，一年中第幾天，夏令時)

1 import time
2 #--------------------------我們先以當前時間為準,讓大家快速認識三種形式的時間
3 print(time.time()) # 時間戳:1487130156.419527
4 print(time.strftime("%Y-%m-%d %X")) #格式化的時間字串:'2017-02-15 11:40:53'
5 
6 print(time.localtime()) #本地時區的struct_time
7 print(time.gmtime())    #UTC時區的struct_time

%a    Locale’s abbreviated weekday name.     
%A    Locale’s full weekday name.     
%b    Locale’s abbreviated month name.     
%B    Locale’s full month name.     
%c    Locale’s appropriate date and time representation.     
%d    Day of the month as a decimal number [01,31].     
%H    Hour (24-hour clock) as a decimal number [00,23].     
%I    Hour (12-hour clock) as a decimal number [01,12].     
%j    Day of the year as a decimal number [001,366].     
%m    Month as a decimal number [01,12].     
%M    Minute as a decimal number [00,59].     
%p    Locale’s equivalent of either AM or PM.    (1)
%S    Second as a decimal number [00,61].    (2)
%U    Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.    (3)
%w    Weekday as a decimal number [0(Sunday),6].     
%W    Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.    (3)
%x    Locale’s appropriate date representation.     
%X    Locale’s appropriate time representation.     
%y    Year without century as a decimal number [00,99].     
%Y    Year with century as a decimal number.     
%z    Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59].     
%Z    Time zone name (no characters if no time zone exists).     
%%    A literal '%' character.

%a    Locale’s abbreviated weekday name.     
%A    Locale’s full weekday name.     
%b    Locale’s abbreviated month name.     
%B    Locale’s full month name.     
%c    Locale’s appropriate date and time representation.     
%d    Day of the month as a decimal number [01,31].     
%H    Hour (24-hour clock) as a decimal number [00,23].     
%I    Hour (12-hour clock) as a decimal number [01,12].     
%j    Day of the year as a decimal number [001,366].     
%m    Month as a decimal number [01,12].     
%M    Minute as a decimal number [00,59].     
%p    Locale’s equivalent of either AM or PM.    (1)
%S    Second as a decimal number [00,61].    (2)
%U    Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.    (3)
%w    Weekday as a decimal number [0(Sunday),6].     
%W    Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.    (3)
%x    Locale’s appropriate date representation.     
%X    Locale’s appropriate time representation.     
%y    Year without century as a decimal number [00,99].     
%Y    Year with century as a decimal number.     
%z    Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59].     
%Z    Time zone name (no characters if no time zone exists).     
%%    A literal '%' character.

其中計算機認識的時間只能是'時間戳'格式，而程式設計師可處理的或者說人類能看懂的時間有: '格式化的時間字串'，'結構化的時間' ，於是有了下圖的轉換關係

 1 #--------------------------按圖1轉換時間
 2 # localtime([secs])
 3 # 將一個時間戳轉換為當前時區的struct_time。secs引數未提供，則以當前時間為準。
 4 time.localtime()
 5 time.localtime(1473525444.037215)
 6 
 7 # gmtime([secs]) 和localtime()方法類似，gmtime()方法是將一個時間戳轉換為UTC時區（0時區）的struct_time。
 8 
 9 # mktime(t) : 將一個struct_time轉化為時間戳。
10 print(time.mktime(time.localtime()))#1473525749.0
11 
12 
13 # strftime(format[, t]) : 把一個代表時間的元組或者struct_time（如由time.localtime()和
14 # time.gmtime()返回）轉化為格式化的時間字串。如果t未指定，將傳入time.localtime()。如果元組中任何一個
15 # 元素越界，ValueError的錯誤將會被丟擲。
16 print(time.strftime("%Y-%m-%d %X", time.localtime()))#2016-09-11 00:49:56
17 
18 # time.strptime(string[, format])
19 # 把一個格式化時間字串轉化為struct_time。實際上它和strftime()是逆操作。
20 print(time.strptime('2011-05-05 16:37:06', '%Y-%m-%d %X'))
21 #time.struct_time(tm_year=2011, tm_mon=5, tm_mday=5, tm_hour=16, tm_min=37, tm_sec=6,
22 #  tm_wday=3, tm_yday=125, tm_isdst=-1)
23 #在這個函式中，format預設為："%a %b %d %H:%M:%S %Y"。

1 #--------------------------按圖2轉換時間
2 # asctime([t]) : 把一個表示時間的元組或者struct_time表示為這種形式：'Sun Jun 20 23:21:05 1993'。
3 # 如果沒有引數，將會將time.localtime()作為引數傳入。
4 print(time.asctime())#Sun Sep 11 00:43:43 2016
5 
6 # ctime([secs]) : 把一個時間戳（按秒計算的浮點數）轉化為time.asctime()的形式。如果引數未給或者為
7 # None的時候，將會預設time.time()為引數。它的作用相當於time.asctime(time.localtime(secs))。
8 print(time.ctime())  # Sun Sep 11 00:46:38 2016
9 print(time.ctime(time.time()))  # Sun Sep 11 00:46:38 2016

1 #--------------------------其他用法
2 # sleep(secs)
3 # 執行緒推遲指定的時間執行，單位為秒。

#時間加減
import datetime

# print(datetime.datetime.now()) #返回 2016-08-19 12:47:03.941925
#print(datetime.date.fromtimestamp(time.time()) )  # 時間戳直接轉成日期格式 2016-08-19
# print(datetime.datetime.now() )
# print(datetime.datetime.now() + datetime.timedelta(3)) #當前時間+3天
# print(datetime.datetime.now() + datetime.timedelta(-3)) #當前時間-3天
# print(datetime.datetime.now() + datetime.timedelta(hours=3)) #當前時間+3小時
# print(datetime.datetime.now() + datetime.timedelta(minutes=30)) #當前時間+30分


#
# c_time  = datetime.datetime.now()
# print(c_time.replace(minute=3,hour=2)) #時間替換

#時間加減
import datetime

# print(datetime.datetime.now()) #返回 2016-08-19 12:47:03.941925
#print(datetime.date.fromtimestamp(time.time()) )  # 時間戳直接轉成日期格式 2016-08-19
# print(datetime.datetime.now() )
# print(datetime.datetime.now() + datetime.timedelta(3)) #當前時間+3天
# print(datetime.datetime.now() + datetime.timedelta(-3)) #當前時間-3天
# print(datetime.datetime.now() + datetime.timedelta(hours=3)) #當前時間+3小時
# print(datetime.datetime.now() + datetime.timedelta(minutes=30)) #當前時間+30分


#
# c_time  = datetime.datetime.now()
# print(c_time.replace(minute=3,hour=2)) #時間替換