利用bat脚本获取当前日期的前n天的日期

    
    @echo off
    rem 假设系统日期的格式为yyyy-mm-dd
    call :DateToDays %date:~0,4% %date:~5,2% %date:~8,2% PassDays
    set /a PassDays-=%DaysAgo%
    call :DaysToDate %PassDays% DstYear DstMonth DstDay
    set DstDate=%DstYear%-%DstMonth%-%DstDay%
    echo %DaysAgo%天的日期是%DstDate%
    pause
    goto :eof

    :DateToDays %yy% %mm% %dd% days
    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

    :DaysToDate %days% yy mm dd
    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

未完待续