Add or subtract days from any date, copy the script below or download here and save as DateMath.cmd
@ECHO off
SETLOCAL
:: DateMath, a general purpose date math routine
:: If DateMath detects an error, variable _dd_int is set to 999999.
SET v_dd_int=0
SET v_mm_int=0
SET v_yy_int=0
SET v_ymd_str=
SET v_mm_str=
SET v_dd_str=
IF "%3"=="" goto s_syntax
IF "%4"=="+" goto s_validate_year
IF "%4"=="-" goto s_validate_year
IF "%4"=="" goto s_validate_year
:s_syntax
echo.
echo DATEMATH SYNTAX:
echo _______________
echo.
echo DateMath will set the variables as listed below
echo 'str' variables include leading zeros e.g. "01"
echo 'int' variables leading zeros are stripped e.g. "1"
echo.
echo CALL DateMath YY MM DD - YY2 MM2 DD2
echo.
echo Will set variable _dd_int to the signed difference
echo between the 2 dates (measured in days)
echo.
echo.
echo CALL DateMath YY MM DD +/- Days
echo.
echo Will set the following variables to the result of
echo adding or substracting days from the initial date:
echo _ymd_str, _yy_int
echo _mm_str, _mm_int,
echo _dd_str, _dd_int
echo.
echo.
echo ___________________________________
pause
echo.
echo.
echo CALL DateMath YY MM DD
echo.
echo Will set the following variables:
echo _ymd_str, _yy_int
echo _mm_str, _mm_int,
echo _dd_str, _dd_int
echo.
echo ___________________________________
echo.
echo _ymd_str is in YYYYMMDD format.
echo.
echo _yy_int is in YYYY format, even if YY format was originally supplied.
echo This conversion is useful for FAT/NTFS file dates which are in YY format.
echo.
ENDLOCAL & SET /a _dd_int=999999
goto :eof
:s_validate_year
::strip leading zeros
SET v_yy=%1
if %v_yy:~0,1% EQU 0 set v_yy=%v_yy:~1%
:: Check for Y2K
IF %v_yy% LSS 100 IF %v_yy% GEQ 80 SET /A v_yy += 1900
IF %v_yy% LSS 80 SET /A v_yy += 2000
:: at this point v_yy contains a 4 digit year
::validate month and day
if %2 GTR 12 goto s_syntax
if %3 GTR 31 goto s_syntax
SET v_mm=%2
SET v_dd=%3
::strip leading zeros
if %v_mm:~0,1% EQU 0 set v_mm=%v_mm:~1%
if %v_dd:~0,1% EQU 0 set v_dd=%v_dd:~1%
:: Set the int variables
SET /a v_dd_int=%v_dd%
SET /a v_yy_int=%v_yy%
SET /a v_mm_int=%v_mm%
:: Determine which function to perform - ADD, SUBTRACT or CONVERT
If not "%6"=="" goto s_validate_2nd_date
if "%4"=="" goto s_convert_only
:: Add or subtract days to a date
SET /a v_number_of_days=%5
goto s_add_or_subtract_days
:s_convert_only
SET /a v_dd_int=%v_dd%
IF %v_dd% LEQ 9 (SET v_dd_str=0%v_dd%) ELSE (SET v_dd_str=%v_dd%)
IF %v_mm% LEQ 9 (SET v_mm_str=0%v_mm%) ELSE (SET v_mm_str=%v_mm%)
SET v_ymd_str=%v_yy%%v_mm_str%%v_dd_str%
ECHO DATEMATH - Convert date only (no maths)
goto s_end
::::::::::::::::::::::::::::::::::::::::::::::::::
:s_validate_2nd_date
If "%4"=="+" goto s_syntax
:: Subtracting one date from another ::::::
:: strip leading zero
SET v_yy2=%5
if %v_yy2:~0,1% EQU 0 set v_yy2=%v_yy2:~1%
if %v_yy2% GTR 99 goto s_validate2nd_month
if %v_yy2% GTR 49 goto s_prefix_2_1950_1999
if %v_yy2% LSS 10 goto s_prefix_2_2000_2009
SET v_yy2=20%v_yy2%
goto s_validate2nd_month
:s_prefix_2_2000_2009
SET v_yy2=200%v_yy2%
goto s_validate2nd_month
:s_prefix_2_1950_1999
SET v_yy2=19%v_yy2%
:s_validate2nd_month
::strip leading zeros
::SET /a v_yy2=%v_yy2%
if %v_yy2:~0,1% EQU 0 set v_yy2=%v_yy2:~1%
::v_yy2 now contains a 4 digit year
if %6 GTR 12 goto s_syntax
SET v_mm2=%6
if %7 GTR 31 goto s_syntax
SET v_dd2=%7
::strip leading zeros
::SET /a v_mm2=%v_mm2%
if %v_mm2:~0,1% EQU 0 set v_mm2=%v_mm2:~1%
::SET /a v_dd2=%v_dd2%
if %v_dd2:~0,1% EQU 0 set v_dd2=%v_dd2:~1%
call :s_julian_day %v_yy_int% %v_mm_int% %v_dd_int%
SET v_sumdays1=%v_JulianDay%
call :s_julian_day %v_yy2% %v_mm2% %v_dd2%
SET v_sumdays2=%v_JulianDay%
SET /a v_dd_int=%v_sumdays1% - %v_sumdays2%
ECHO DATEMATH - Subtracting one date from another = days difference
ECHO ~~~~~~
ECHO %v_dd_int%
ECHO ~~~~~~
goto s_end_days
::::::::::::::::::::::::::::::::::::::::::::::::::
:s_add_or_subtract_days
if /i "%4"=="+" goto s_add_up_days
:: Subtract all days ::::::
SET /a v_dd=%v_dd% - %v_number_of_days%
:s_adjust_month_year
if %v_dd% GEQ 1 goto s_add_subtract_days_DONE
SET /a v_mm=%v_mm% - 1
if %v_mm% GEQ 1 goto s_add_days_%v_mm%
SET /a v_yy=%v_yy% - 1
SET /a v_mm=%v_mm% + 12
goto s_add_days_%v_mm%
:s_add_days_2
SET /a v_dd=%v_dd% + 28
SET /a v_leapyear=%v_yy% / 4
SET /a v_leapyear=%v_leapyear% * 4
if %v_leapyear% NEQ %v_yy% goto s_adjust_month_year
SET /a v_dd=%v_dd% + 1
goto s_adjust_month_year
:s_add_days_4
:s_add_days_6
:s_add_days_9
:s_add_days_11
SET /a v_dd=%v_dd% + 30
goto s_adjust_month_year
:s_add_days_1
:s_add_days_3
:s_add_days_5
:s_add_days_7
:s_add_days_8
:s_add_days_10
:s_add_days_12
SET /a v_dd=%v_dd% + 31
goto s_adjust_month_year
:s_add_up_days
:: add all days ::::::
SET /a v_dd=%v_dd% + %v_number_of_days%
:s_subtract_days_
goto s_subtract_days_%v_mm%
:s_adjust_mth_yr
SET /a v_mm=%v_mm% + 1
if %v_mm% LEQ 12 goto s_subtract_days_%v_mm%
SET /a v_yy=%v_yy% + 1
SET /a v_mm=%v_mm% - 12
goto s_subtract_days_%v_mm%
:s_subtract_days_2
SET /a v_leapyear=%v_yy% / 4
SET /a v_leapyear=%v_leapyear% * 4
If %v_leapyear% EQU %v_yy% goto s_subtract_leapyear
if %v_dd% LEQ 28 goto s_add_subtract_days_DONE
SET /a v_dd=%v_dd% - 28
goto s_adjust_mth_yr
:s_subtract_leapyear
if %v_dd% LEQ 29 goto s_add_subtract_days_DONE
SET /a v_dd=%v_dd% - 29
goto s_adjust_mth_yr
:s_subtract_days_4
:s_subtract_days_6
:s_subtract_days_9
:s_subtract_days_11
if %v_dd% LEQ 30 goto s_add_subtract_days_DONE
SET /a v_dd=%v_dd% - 30
goto s_adjust_mth_yr
:s_subtract_days_1
:s_subtract_days_3
:s_subtract_days_5
:s_subtract_days_7
:s_subtract_days_8
:s_subtract_days_10
:s_subtract_days_12
if %v_dd% LEQ 31 goto s_add_subtract_days_DONE
SET /a v_dd=%v_dd% - 31
goto s_adjust_mth_yr
:s_add_subtract_days_DONE
SET /a v_dd_int=%v_dd%
SET /a v_mm_int=%v_mm%
SET /a v_yy_int=%v_yy%
IF %v_dd% GTR 9 (SET v_dd_str=%v_dd%) ELSE (SET v_dd_str=0%v_dd%)
IF %v_mm% GTR 9 (SET v_mm_str=%v_mm%) ELSE (SET v_mm_str=0%v_mm%)
SET v_ymd_str=%v_yy%%v_mm_str%%v_dd_str%
ECHO DATEMATH - add or subtract days from a date = new date
goto s_end
::::::::::::::::::::::::::::::::::::::::::::::::::
:s_julian_day
SET v_year=%1
SET v_month=%2
SET v_day=%3
SET /a v_month=v_month
SET /a v_day=v_day
SET /A a = 14 - v_month
SET /A a /= 12
SET /A y = v_year + 4800 - a
SET /A m = v_month + 12 * a - 3
SET /A m = 153 * m + 2
SET /A m /= 5
SET /A v_JulianDay = v_day + m + 365 * y + y / 4 - y / 100 + y / 400 - 32045
ECHO The Julian Day is [%v_JulianDay%]
goto :eof
::::::::::::::::::::::::::::::::::::::::::::::::::
:s_end
ECHO ~~~~~~~~~~~~
ECHO [%v_ymd_str%] YY=[%v_yy_int%] MM=[%v_mm_str%] DD=[%v_dd_str%]
ECHO ~~~~~~~~~~~~
:s_end_days
ENDLOCAL&SET /a _yy_int=%v_yy_int%&SET /a _mm_int=%v_mm_int%&SET /a _dd_int=%v_dd_int%&SET _ymd_str=%v_ymd_str%&SET _mm_str=%v_mm_str%&SET _dd_str=%v_dd_str%
Examples
D:\> datemath 02 05 08
DATEMATH - Convert date only (no maths)
~~~~~~~~~~~~
[20020508] YY=[2002] MM=[05] DD=[08]
~~~~~~~~~~~~
D:\> datemath 2007 12 30
DATEMATH - Convert date only (no maths)
~~~~~~~~~~~~
[20071230] YY=[2007] MM=[12] DD=[30]
~~~~~~~~~~~~
D:\> datemath 27 12 01 - 02 11 02
The Julian Day is [2461741]
The Julian Day is [2452581]
DATEMATH - Subtracting one date from another = days difference
~~~~~~
9160
~~~~~~
D:\> datemath 02 11 02 + 9160
DATEMATH - add or subtract days from a date = new date
~~~~~~~~~~~~
[20271201] YY=[2027] MM=[12] DD=[01]
~~~~~~~~~~~~
D:\> datemath 2012 09 08 - 2011 09 08
The Julian Day is [2456179]
The Julian Day is [2455813]
DATEMATH - Subtracting one date from another = days difference
~~~~~~
366
~~~~~~
D:\> datemath 13 09 08 - 12 09 08
The Julian Day is [2456544]
The Julian Day is [2456179]
DATEMATH - Subtracting one date from another = days difference
~~~~~~
365
~~~~~~
2009-06-03 : Changed the DateMath.cmd variable names returned to match DelOlder.cmd
“We were having one of those great first dates you can only have when it's not an actual date” ~ Sarah Jessica Parker
Related:
SetLocal - Control the visibility of environment variables in a batch file.
Powershell variables - these support Math operations out of the box (.addDays)
Rules for how CMD.EXE parses numbers - DosTips forum (Dave Benham)
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