datetime.datetime.now()時間格式轉化是碰到的問題

import datetime

print datetime.datetime.now()

# 2016-03-28 17:16:00.812000

a = ‘2016-03-28 17:16:00.812000’

timeArray = time.strptime(a, '%Y-%m-%d %H:%M:%S.%f')   ##注意： %f是microseconds的格式化符號。

print timeArray

#time.struct_time(tm_year=2016, tm_mon=3, tm_mday=28, tm_hour=17, tm_min=22, tm_sec=38, tm_wday=0, tm_yday=88, tm_isdst=-1)

 

a = datetime.datetime.now()
print a                                  ## a變量不指向一個字符串對象，而是指向一個datetime.datetime類型的對象
# 2016-03-28 17:24:52.571000
timeArray = time.strptime(a, '%Y-%m-%d %H:%M:%S.%f')    ## 全部這裏報錯。 time.striptime的第一個參數，應該是字符串對象

Traceback (most recent call last):           
  File "<console>", line 1, in <module>
  File "C:\Python27\lib\_strptime.py", line 467, in _strptime_time
    return _strptime(data_string, format)[0]
  File "C:\Python27\lib\_strptime.py", line 322, in _strptime
    found = format_regex.match(data_string)
TypeError: expected string or buffer