@echo off
SET DateStr=%~2&if "%~2"=="" set DateStr=%date%
FOR /F "skip=1 tokens=2-4 delims=(-)" %%a IN ('"echo.|date"') DO (
    FOR /F "TOKENS=1-3 DELIMS=/.- " %%A IN ("%DateStr:* =%") DO (
        SET %%a=%%A&set %%b=%%B&set %%c=%%C))
SET /A "yy=10000%yy% %%10000,mm=100%mm% %% 100,dd=100%dd% %% 100"
SET /A JD=dd-32075+1461*(yy+4800+(mm-14)/12)/4+367*(mm-2-(mm-14)/12*12)/12-3*((yy+4900+(mm-14)/12)/100)/4
IF "%~1" NEQ "" (SET %~1=%JD%) ELSE (SET /P ".=%JD%"<nul)

exit /b