Subtract datetime objects to get numerical result in milliseconds (Python) -

trying find elapsed time 2 strings hold timestamp , in format hh:mm:ss.mss. basically, want subtract 2 datetime objects , numerical result in milliseconds.

here code:

from datetime import datetime  elapsed_time = 0 s = '13:46:34.550' e = '13:46:36.750'  # interested on time part, not date start_time = datetime.strptime(s, '%h:%m:%s.%f') end_time   = datetime.strptime(e, '%h:%m:%s.%f')  #elapsed_time = end_time - start_time #elapsed_time = (end_time - start_time).microsecond 

for both elapsed_time calculations typeerror: unsupported operand type(s) -: 'datetime.datetime' , 'int'.

it should print 00:00:02.250 or (ideally) 2200.

any ideas doing wrong?

the following worked me (using python 3.5.2):

from datetime import datetime  elapsed_time = 0 s = '13:46:34.550' e = '13:46:36.750'  # interested on time part, not date start_time = datetime.strptime(s, '%h:%m:%s.%f') end_time = datetime.strptime(e, '%h:%m:%s.%f')  diff = end_time - start_time elapsed_time = int((diff.seconds * 1000) + (diff.microseconds / 1000)) 

the output got 2200 time difference in milliseconds between s , e

some references:

python: difference between 2 datetimes in milliseconds (mark needham's blog)

python docs datetime

a bit of explanation docs (linked above):

in section 8.1.4 datetime objects, states operation:

timedelta = datetime1 - datetime2 

(which corresponds 2nd last line of code in answer):

subtraction of datetime datetime defined if both operands naive, or if both aware. if 1 aware , other naive, typeerror raised.

also:

changed in version 3.3: equality comparisons between naive , aware datetime instances don’t raise typeerror