Calculate time difference in Windows batch file

@echo off

rem Get start time:
for /F "tokens=1-4 delims=:.," %%a in ("%time%") do (
   set /A "start=(((%%a*60)+1%%b %% 100)*60+1%%c %% 100)*100+1%%d %% 100"
)

rem Any process here...

rem Get end time:
for /F "tokens=1-4 delims=:.," %%a in ("%time%") do (
   set /A "end=(((%%a*60)+1%%b %% 100)*60+1%%c %% 100)*100+1%%d %% 100"
)

rem Get elapsed time:
set /A elapsed=end-start

rem Show elapsed time:
set /A hh=elapsed/(60*60*100), rest=elapsed%%(60*60*100), mm=rest/(60*100), rest%%=60*100, ss=rest/100, cc=rest%%100
if %mm% lss 10 set mm=0%mm%
if %ss% lss 10 set ss=0%ss%
if %cc% lss 10 set cc=0%cc%
echo %hh%:%mm%:%ss%,%cc%

EDIT 2017-05-09: Shorter method added

I developed a shorter method to get the same result, so I couldn’t resist to post it here. The two for commands used to separate time parts and the three if commands used to insert leading zeros in the result are replaced by two long arithmetic expressions, that could even be combined into a single longer line.

The method consists in directly convert a variable with a time in “HH:MM:SS.CC” format into the formula needed to convert the time to centiseconds, accordingly to the mapping scheme given below:

       HH        :      MM        :      SS        .       CC

(((10  HH  %%100)*60+1  MM  %%100)*60+1  SS  %%100)*100+1  CC  %%100

That is, insert (((10 at beginning, replace the colons by %%100)*60+1, replace the point by %%100)*100+1 and insert %%100 at end; finally, evaluate the resulting string as an arithmetic expression. In the time variable there are two different substrings that needs to be replaced, so the conversion must be completed in two lines. To get an elapsed time, use (endTime)-(startTime) expression and replace both time strings in the same line.

EDIT 2017/06/14: Locale independent adjustment added

EDIT 2020/06/05: Pass-over-midnight adjustment added

@echo off
setlocal EnableDelayedExpansion

set "startTime=%time: =0%"

set /P "=Any process here..."

set "endTime=%time: =0%"



rem Get elapsed time:
set "end=!endTime:%time:~8,1%=%%100)*100+1!"  &  set "start=!startTime:%time:~8,1%=%%100)*100+1!"
set /A "elap=((((10!end:%time:~2,1%=%%100)*60+1!%%100)-((((10!start:%time:~2,1%=%%100)*60+1!%%100), elap-=(elap>>31)*24*60*60*100"

rem Convert elapsed time to HH:MM:SS:CC format:
set /A "cc=elap%%100+100,elap/=100,ss=elap%%60+100,elap/=60,mm=elap%%60+100,hh=elap/60+100"

echo Start:    %startTime%
echo End:      %endTime%
echo Elapsed:  %hh:~1%%time:~2,1%%mm:~1%%time:~2,1%%ss:~1%%time:~8,1%%cc:~1%

You may review a detailed explanation of this method at this answer.

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