Source code for dateadd.bat

```
@ECHO OFF
```
```
ECHO.
```
```
 
```
```
:: Check the Windows version
```
```
IF NOT "%OS%"=="Windows_NT" GOTO Syntax
```
```
SETLOCAL
```
```
 
```
```
:: Initialize variable
```
```
SET Error=0
```
```
 
```
```
:: Check the command line arguments
```
```
IF     "%~1"=="" GOTO Syntax
```
```
IF NOT "%~3"=="" GOTO Syntax
```
```
IF "%~2"=="" (
```
```
	FOR %%A IN (%Date%) DO SET cDate=%%A
```
```
	SET cDays=%~1
```
```
) ELSE (
```
```
	SET cDate=%~1
```
```
	SET cDays=%~2
```
```
)
```
```
 
```

:: Read the Date format from the registry

```
CALL :ReadDateFormat
```
```
 
```
```
:: Check if a valid date was specified
```

(ECHO.%cDate%) | FINDSTR /R /B /C:"[0-9]*\%sDate%[0-9]*\%sDate%[0-9]*" >NUL

```
IF ERRORLEVEL 1 (
```

	ECHO Error: %cDate% is not a valid date

```
	ECHO.
```
```
	GOTO Syntax
```
```
)
```
```
 
```

:: Check if the second argument is a valid number

(ECHO.%cDays%) | FINDSTR /R /B /C:"-*[0-9]*" >NUL

```
IF ERRORLEVEL 1 (
```
```
	ECHO Error: %cDays% is not an integer
```
```
	ECHO.
```
```
	GOTO Syntax
```
```
)
```
```
 
```
```
:: Parse the date specified
```
```
CALL :ParseDate %cDate%
```
```
 
```
```
:: Check for errors
```
```
IF %Error% NEQ 0 GOTO Syntax
```
```
 
```

:: Convert the parsed Gregorian date to Julian

```
CALL :JDate %GYear% %GMonth% %GDay%
```
```
 
```
```
:: Display original input
```
```
ECHO Starting date   : %cDate%
```
```
 
```

:: Add or subtract the specified number of days

```
IF "%cDays:~0,1%"=="-" (
```
```
	SET /A NewJDate = %JDate% - %cDays:~1%
```
```
	ECHO Days subtracted : %cDays:~1%
```
```
) ELSE (
```
```
	SET /A NewJDate = %JDate% + %cDays%
```
```
	ECHO Days added      : %cDays%
```
```
)
```
```
 
```

:: Convert the new Julian date back to Gregorian again

```
CALL :GDate %NewJDate%
```
```
 
```
```
:: Reformat the date to local format
```
```
CALL :ReformatDate %GDate%
```
```
 
```
```
:: Display the result
```
```
ECHO Resulting date  : %LDate%
```
```
 
```

:: Return the result in a variable named after this batch file

```
ENDLOCAL & SET %~n0=%LDate%
```
```
GOTO:EOF
```
```
 
```
```
 
```
```
::===================================::
```
```
::                                   ::
```
```
::   -   S u b r o u t i n e s   -   ::
```
```
::                                   ::
```
```
::===================================::
```
```
 
```
```
 
```
```
:GDate
```

:: Convert Julian date back to "normal" Gregorian date

```
:: Argument : Julian date
```
```
:: Returns  : YYYY MM DD
```
```
::
```

:: Algorithm based on Fliegel-Van Flandern

:: algorithm from the Astronomical Almanac,

:: provided by Doctor Fenton on the Math Forum

:: (http://mathforum.org/library/drmath/view/51907.html),

:: and converted to batch code by Ron Bakowski.

```
::
```
```
SET /A P      = %1 + 68569
```
```
SET /A Q      = 4 * %P% / 146097
```

SET /A R      = %P% - ( 146097 * %Q% +3 ) / 4

SET /A S      = 4000 * ( %R% + 1 ) / 1461001

SET /A T      = %R% - 1461 * %S% / 4 + 31

```
SET /A U      = 80 * %T% / 2447
```
```
SET /A V      = %U% / 11
```

SET /A GYear  = 100 * ( %Q% - 49 ) + %S% + %V%

```
SET /A GMonth = %U% + 2 - 12 * %V%
```
```
SET /A GDay   = %T% - 2447 * %U% / 80
```
```
:: Clean up the mess
```
```
FOR %%A IN (P Q R S T U V) DO SET %%A=
```
```
:: Add leading zeroes
```

IF 1%GMonth% LSS 20 SET GMonth=0%GMonth%

```
IF 1%GDay%   LSS 20 SET GDay=0%GDay%
```
```
:: Return value
```
```
SET GDate=%GYear% %GMonth% %GDay%
```
```
GOTO:EOF
```
```
 
```
```
 
```
```
:JDate
```
```
:: Convert date to Julian
```
```
:: Arguments : YYYY MM DD
```
```
:: Returns   : Julian date
```
```
::
```
```
:: First strip leading zeroes
```
```
SET MM=%2
```
```
SET DD=%3
```
```
IF %MM:~0,1% EQU 0 SET MM=%MM:~1%
```
```
IF %DD:~0,1% EQU 0 SET DD=%DD:~1%
```
```
::
```

:: Algorithm based on Fliegel-Van Flandern

:: algorithm from the Astronomical Almanac,

:: provided by Doctor Fenton on the Math Forum

:: (http://mathforum.org/library/drmath/view/51907.html),

:: and converted to batch code by Ron Bakowski.

```
SET /A Month1 = ( %MM% - 14 ) / 12
```
```
SET /A Year1  = %1 + 4800
```

SET /A JDate  = 1461 * ( %Year1% + %Month1% ) / 4 + 367 * ( %MM% - 2 -12 * %Month1% ) / 12 - ( 3 * ( ( %Year1% + %Month1% + 100 ) / 100 ) ) / 4 + %DD% - 32075

```
FOR %%A IN (Month1 Year1) DO SET %%A=
```
```
GOTO:EOF 
```
```
 
```
```
 
```
```
:ParseDate
```

:: Parse (Gregorian) date depending on registry's date format settings

:: Argument : Gregorian date in local date format,

:: Requires : sDate (local date separator), iDate (local date format number)

:: Returns  : GYear (4-digit year), GMonth (2-digit month), GDay (2-digit day)

```
::
```

IF %iDate%==0 FOR /F "TOKENS=1-3 DELIMS=%sDate%" %%A IN ('ECHO.%1') DO (

```
	SET GYear=%%C
```
```
	SET GMonth=%%A
```
```
	SET GDay=%%B
```
```
)
```

IF %iDate%==1 FOR /F "TOKENS=1-3 DELIMS=%sDate%" %%A IN ('ECHO.%1') DO (

```
	SET GYear=%%C
```
```
	SET GMonth=%%B
```
```
	SET GDay=%%A
```
```
)
```

IF %iDate%==2 FOR /F "TOKENS=1-3 DELIMS=%sDate%" %%A IN ('ECHO.%1') DO (

```
	SET GYear=%%A
```
```
	SET GMonth=%%B
```
```
	SET GDay=%%C
```
```
)
```
```
IF %GDay%   GTR 31 SET Error=1
```
```
IF %GMonth% GTR 12 SET Error=1
```
```
GOTO:EOF
```
```
 
```
```
 
```
```
:ReadDateFormat
```

:: Read the Date format from the registry.

```
:: Arguments : none
```

:: Returns   : sDate (separator), iDate (date format number)

```
::
```

:: First, export registry settings to a temporary file:

START /W REGEDIT /E "%TEMP%.\_TEMP.REG" "HKEY_CURRENT_USER\Control Panel\International"

```
:: Now, read the exported data:
```

FOR /F "tokens=1* delims==" %%A IN ('TYPE "%TEMP%.\_TEMP.REG" ^| FIND /I "iDate"') DO SET iDate=%%B

FOR /F "tokens=1* delims==" %%A IN ('TYPE "%TEMP%.\_TEMP.REG" ^| FIND /I "sDate"') DO SET sDate=%%B

```
:: Remove the temporary file:
```
```
DEL "%TEMP%.\_TEMP.REG"
```
```
:: Remove quotes from the data read:
```
```
:: SET iDate=%iDate:"=%
```
```
FOR %%A IN (%iDate%) DO SET iDate=%%~A
```
```
:: SET sDate=%sDate:"=%
```
```
FOR %%A IN (%sDate%) DO SET sDate=%%~A
```
```
GOTO:EOF
```
```
 
```
```
 
```
```
:ReformatDate
```

:: Reformat the date back to the local format

```
:: Arguments : YYYY MM DD
```

:: Returns   : LDate (Gregorian date in local format)

```
::
```

IF %iDate%==0 SET LDate=%2%sDate%%3%sDate%%1

IF %iDate%==1 SET LDate=%3%sDate%%2%sDate%%1

IF %iDate%==2 SET LDate=%1%sDate%%2%sDate%%3

```
GOTO:EOF
```
```
 
```
```
 
```
```
:Syntax
```

ECHO DateAdd.bat,  Version 1.10 for Windows NT 4 / 2000 / XP / Server 2003 / Vista

ECHO Add (or subtract) the specified number of days to (or from) the specified date

```
ECHO.
```
```
ECHO Usage:  DATEADD  [ date ]  days
```
```
ECHO.
```

ECHO Where:  "date"   is a "normal" Gregorian date in the local computer's format

ECHO                  (default value if no date is specified: today's date)

ECHO         "days"   is the number of days to add or subtract

```
ECHO.
```

IF     "%OS%"=="Windows_NT" FOR %%A IN (%Date%) DO SET Today=%%A

IF     "%OS%"=="Windows_NT" ECHO E.g.    DATEADD %Today%  1 will return tomorrow's date  (as will DATEADD  1)

IF     "%OS%"=="Windows_NT" ECHO         DATEADD %Today% -1 will return yesterday's date (as will DATEADD -1)

```
IF     "%OS%"=="Windows_NT" ENDLOCAL
```

IF NOT "%OS%"=="Windows_NT" ECHO E.g.    DATEADD 01/25/2007  1 should return 01/26/2007

IF NOT "%OS%"=="Windows_NT" ECHO         DATEADD 01/25/2007 -1 should return 01/24/2007

```
ECHO.
```

ECHO Julian date conversion based on Fliegel-Van Flandern algorithms from

ECHO the Astronomical Almanac, provided by Doctor Fenton on the Math Forum

ECHO (http://mathforum.org/library/drmath/view/51907.html), and converted

```
ECHO to batch code by Ron Bakowski.
```
```
ECHO.
```
```
ECHO Written by Rob van der Woude
```
```
ECHO http://www.robvanderwoude.com
```
```
 
```