Batch : Affichage de la date moins 3 jours

@echo off
for /F "tokens=1,2,3 delims=/" %%I in ('date /T') do call :DateToDays %%K %%J %%I days
::echo/%days%
set /A nday=%days%-3
::echo/%nday%
call :DaysToDate %nday% yyyy mm dd
::call :DaysToDate %1 yy mm dd
set ndatealt=%dd%/%mm%/%yy%
::echo/%yy%-%mm%-%dd%
echo %ndatealt%

goto :EOF

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:DaysToDate %days% yy mm dd
::
:: By: Ritchie Lawrence, 2002-06-15. Version 1.1
::
:: Func: Returns a calendar date from the number of elapsed days since 1st
::       January 1970. For NT4/2K/XP.
:: 
:: Args: %1 MJD used to create calendar date (by val)
::       %2 var to receive year component, 4 digits (by ref)
::       %3 var to receive month component, 2 digits, 01-12 (by ref)
::       %4 var to receive day of month component, 2 digits, 01-31 (by ref)
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
setlocal ENABLEEXTENSIONS
set /a a=%1+2472632,b=4*a+3,b/=146097,c=-b*146097,c/=4,c+=a
set /a d=4*c+3,d/=1461,e=-1461*d,e/=4,e+=c,m=5*e+2,m/=153,dd=153*m+2,dd/=5
set /a dd=-dd+e+1,mm=-m/10,mm*=12,mm+=m+3,yy=b*100+d-4800+m/10
(if %mm% LSS 10 set mm=0%mm%)&(if %dd% LSS 10 set dd=0%dd%)
endlocal&set %2=%yy%&set %3=%mm%&set %4=%dd%&goto :EOF
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
goto :EOF

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:DateToDays %yy% %mm% %dd% days
::
:: By:   Ritchie Lawrence, 2002-09-26. Version 1.0
::
:: Func: Returns the number of days elapsed since 1st January 1970 for a
::       given date. For NT4/2K/XP
:: 
:: Args: %1 year component used to create days, 2 or 4 digits (by val)
::       %2 month component used to create days, leading zero ok (by val)
::       %3 date of month used to create days, leading zero ok (by val)
::       %4 var to receive number of elapsed days (by ref)
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
setlocal ENABLEEXTENSIONS
set yy=%1&set mm=%2&set dd=%3
if 1%yy% LSS 200 if 1%yy% LSS 170 (set yy=20%yy%) else (set yy=19%yy%)
set /a dd=100%dd%%%100,mm=100%mm%%%100
set /a z=14-mm,z/=12,y=yy+4800-z,m=mm+12*z-3,j=153*m+2
set /a j=j/5+dd+y*365+y/4-y/100+y/400-2472633
endlocal&set %4=%j%&goto :EOF
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

C:> .\date -d "3 days ago"
Mon May 20 12:40:52 
C:>

@echo off
::for /F "tokens=1,2,3 delims=/" %%I in ('date /T') do call :DateToDays %%K %%J %%I days

for /f "tokens=1,2,3 delims=/" %%I in ("%1") do call :DateToDays %%K %%J %%I days

echo/%days%
set /A nday=%days%-3
echo/%nday%
call :DaysToDate %nday% yyyy mm dd
::call :DaysToDate %1 yy mm dd
set ndatealt=%dd%/%mm%/%yy%
::echo/%yy%-%mm%-%dd%
echo %ndatealt%

goto :EOF

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:DaysToDate %days% yy mm dd
::
:: By: Ritchie Lawrence, 2002-06-15. Version 1.1
::
:: Func: Returns a calendar date from the number of elapsed days since 1st
::       January 1970. For NT4/2K/XP.
:: 
:: Args: %1 MJD used to create calendar date (by val)
::       %2 var to receive year component, 4 digits (by ref)
::       %3 var to receive month component, 2 digits, 01-12 (by ref)
::       %4 var to receive day of month component, 2 digits, 01-31 (by ref)
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
setlocal ENABLEEXTENSIONS
set /a a=%1+2472632,b=4*a+3,b/=146097,c=-b*146097,c/=4,c+=a
set /a d=4*c+3,d/=1461,e=-1461*d,e/=4,e+=c,m=5*e+2,m/=153,dd=153*m+2,dd/=5
set /a dd=-dd+e+1,mm=-m/10,mm*=12,mm+=m+3,yy=b*100+d-4800+m/10
(if %mm% LSS 10 set mm=0%mm%)&(if %dd% LSS 10 set dd=0%dd%)
endlocal&set %2=%yy%&set %3=%mm%&set %4=%dd%&goto :EOF
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
goto :EOF

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:DateToDays %yy% %mm% %dd% days
::
:: By:   Ritchie Lawrence, 2002-09-26. Version 1.0
::
:: Func: Returns the number of days elapsed since 1st January 1970 for a
::       given date. For NT4/2K/XP
:: 
:: Args: %1 year component used to create days, 2 or 4 digits (by val)
::       %2 month component used to create days, leading zero ok (by val)
::       %3 date of month used to create days, leading zero ok (by val)
::       %4 var to receive number of elapsed days (by ref)
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
setlocal ENABLEEXTENSIONS
set yy=%1&set mm=%2&set dd=%3
if 1%yy% LSS 200 if 1%yy% LSS 170 (set yy=20%yy%) else (set yy=19%yy%)
set /a dd=100%dd%%%100,mm=100%mm%%%100
set /a z=14-mm,z/=12,y=yy+4800-z,m=mm+12*z-3,j=153*m+2
set /a j=j/5+dd+y*365+y/4-y/100+y/400-2472633
endlocal&set %4=%j%&goto :EOF
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

C:\temp\Work>ttd 02/01/2014
16072
16069
30/12/2013

C:\temp\Work>