python的time和date处理

内置模块time包含很多与时间相关函数。我们可通过它获得当前的时间和格式化时间输出。

time()，以浮点形式返回自Linux新世纪以来经过的秒数。在linux中，00:00:00 UTC, January 1, 1970是新**49**的开始。

strftime可以用来获得当前时间，可以将时间格式化为字符串等等，还挺方便的。但是需要注意的是获得的时间是服务器的时间，注意时区问题，比如gae撒谎那个的时间就是格林尼治时间的0时区，需要自己转换。

strftime（）函数将时间格式化
我们可以使用strftime（）函数将时间格式化为我们想要的格式。它的原型如下：

size_t strftime(
char *strDest,
size_t maxsize,
const char *format,
const struct tm *timeptr
);

我们可以根据format指向字符串中格式命令把timeptr中保存的时间信息放在strDest指向的字符串中，最多向strDest中存放maxsize个字符。该函数返回向strDest指向的字符串中放置的字符数。

strftime使时间格式化。python的strftime格式是C库支持的时间格式的真子集。

　　%a 星期几的简写 Weekday name, abbr.
　　%A 星期几的全称 Weekday name, full
　　%b 月分的简写 Month name, abbr.
　　%B 月份的全称 Month name, full
　　%c 标准的日期的时间串 Complete date and time representation
　　%d 十进制表示的每月的第几天 Day of the month
　　%H 24小时制的小时 Hour (24-hour clock)
　　%I 12小时制的小时 Hour (12-hour clock)
　　%j 十进制表示的每年的第几天 Day of the year
　　%m 十进制表示的月份 Month number
　　%M 十时制表示的分钟数 Minute number
　　%S 十进制的秒数 Second number
　　%U 第年的第几周，把星期日做为第一天（值从0到53）Week number (Sunday first weekday)
　　%w 十进制表示的星期几（值从0到6，星期天为0）weekday number
　　%W 每年的第几周，把星期一做为第一天（值从0到53） Week number (Monday first weekday)
　　%x 标准的日期串 Complete date representation (e.g. 13/01/08)
　　%X 标准的时间串 Complete time representation (e.g. 17:02:10)
　　%y 不带世纪的十进制年份（值从0到99）Year number within century
　　%Y 带世纪部分的十制年份 Year number
　　%z，%Z 时区名称，如果不能得到时区名称则返回空字符。Name of time zone
　　%% 百分号

1. # handling date/time data
   2. # Python23 tested vegaseat 3/6/2005
   3.
   4. import time
   5.
   6. print "List the functions within module time:"
   7. for funk in dir(time):
   8. print funk
   9.
  10. print time.time(), "seconds since 1/1/1970 00:00:00"
  11. print time.time()/(60*60*24), "days since 1/1/1970"
  12.
  13. # time.clock() gives wallclock seconds, accuracy better than 1 ms
  14. # time.clock() is for windows, time.time() is more portable
  15. print "Using time.clock() = ", time.clock(), "seconds since first call to clock()"
  16. print "\nTiming a 1 million loop 'for loop' ..."
  17. start = time.clock()
  18. for x in range(1000000):
  19. y = x # do something
  20. end = time.clock()
  21. print "Time elapsed = ", end - start, "seconds"
  22.
  23. # create a tuple of local time data
  24. timeHere = time.localtime()
  25. print "\nA tuple of local date/time data using time.localtime():"
  26. print "(year,month,day,hour,min,sec,weekday(Monday=0),yearday,dls-flag)"
  27. print timeHere
  28.
  29. # extract a more readable date/time from the tuple
  30. # eg. Sat Mar 05 22:51:55 2005
  31. print "\nUsing time.asctime(time.localtime()):", time.asctime(time.localtime())
  32. # the same results
  33. print "\nUsing time.ctime(time.time()):", time.ctime(time.time())
  34. print "\nOr using time.ctime():", time.ctime()
  35.
  36. print "\nUsing strftime():"
  37. print "Day and Date:", time.strftime("%a %m/%d/%y", time.localtime())
  38. print "Day, Date :", time.strftime("%A, %B %d, %Y", time.localtime())
  39. print "Time (12hr) :", time.strftime("%I:%M:%S %p", time.localtime())
  40. print "Time (24hr) :", time.strftime("%H:%M:%S", time.localtime())
  41. print "DayMonthYear:",time.strftime("%d%b%Y", time.localtime())
  42.
  43. print
  44.
  45. print "Start a line with this date-time stamp and it will sort:",\
  46. time.strftime("%Y/%m/%d %H:%M:%S", time.localtime())
  47.
  48. print
  49.
  50. def getDayOfWeek(dateString):
  51. # day of week (Monday = 0) of a given month/day/year
  52. t1 = time.strptime(dateString,"%m/%d/%Y")
  53. # year in time_struct t1 can not go below 1970 (start of epoch)!
  54. t2 = time.mktime(t1)
  55. return(time.localtime(t2)[6])
  56.
  57. Weekday = ['Monday', 'Tuesday', 'Wednesday', 'Thursday',
  58. 'Friday', 'Saturday', 'Sunday']
  59.
  60. # sorry about the limitations, stay above 01/01/1970
  61. # more exactly 01/01/1970 at 0 UT (midnight Greenwich, England)
  62. print "11/12/1970 was a", Weekday[getDayOfWeek("11/12/1970")]
  63.
  64. print
  65.
  66. print "Calculate difference between two times (12 hour format) of a day:"
  67. time1 = raw_input("Enter first time (format 11:25:00AM or 03:15:30PM): ")
  68. # pick some plausible date
  69. timeString1 = "03/06/05 " + time1
  70. # create a time tuple from this time string format eg. 03/06/05 11:22:00AM
  71. timeTuple1 = time.strptime(timeString1, "%m/%d/%y %I:%M:%S%p")
  72.
  73. #print timeTuple1 # test eg. (2005, 3, 6, 11, 22, 0, 5, 91, -1)
  74.
  75. time2 = raw_input("Enter second time (format 11:25:00AM or 03:15:30PM): ")
  76. # use same date to stay in same day
  77. timeString2 = "03/06/05 " + time2
  78. timeTuple2 = time.strptime(timeString2, "%m/%d/%y %I:%M:%S%p")
  79.
  80. # mktime() gives seconds since epoch 1/1/1970 00:00:00
  81. time_difference = time.mktime(timeTuple2) - time.mktime(timeTuple1)
  82. #print type(time_difference) # test <type 'float'>
  83. print "Time difference = %d seconds" % int(time_difference)
  84. print "Time difference = %0.1f minutes" % (time_difference/60.0)
  85. print "Time difference = %0.2f hours" % (time_difference/(60.0*60))
  86.
  87. print
  88.
  89. print "Wait one and a half seconds!"
  90. time.sleep(1.5)
  91. print "The end!"