中国DOS联盟

原帖地址：
http://groups.google.com/group/alt.msdos.batch.nt/browse_thread/thread/4cc47d72586a2e73

Okay, here is my final bisection thing, but it's now written
in only ONE Line.
That line is very long, exact 418 visible char long:
(if not defined Result ... goto%0

Two things are required: ".BAT" extension, and a variable
named Result must be empty.


The testing loop, in (2147483647, -33554428, 0),
would count down from 2147483647, and stop on 255.


If a loop with that same speed for each number you see, it would
have calc/found that number after more than four years. In other
words: if you run the test loop (take about 4 seconds), and then
see a message: 255. "All Done", Press any key ..., then you have
displayed the same data as would have taken more than 260 years,
So, I would say this loop is fast. Besides that, it shouldn't be
a problem for you to rewrite it for whatever, other purpose than
exit-codes/errorlevels...


Benny


@echo off
setlocal enabledelayedexpansion
(set Result=)
for /L %%I in (2147483647, -33554428, 0) do (
call :ErrMake %%I
call :ErrFind > nul
echo !ErrFind!.
REM if "!ErrFind!" neq "%%I" echo OOPS.& exit /b
)
endlocal
call:_& echo All Done.& pause
goto:eof


:ErrFind
(if "!Result!"=="" set Result=%0&set Result=!Result:~1!&(if not errorlevel 1 set !Result!=0&set Result=&goto:eof)&set H=2147483647&(if errorlevel !H! set !Result!=!H!&set Result=&goto:eof)&set L=0)&set/a A=H/2+L/2&echo H:!H! A:!A! L:!L!&(if errorlevel !A! ((if !L!==!A! set/a A+=1&(if not errorlevel !A! set A=!L!)&set !Result!=!A!&set Result=&goto:eof)&set L=!A!)else set H=!A!)&goto%0


:ErrMake X
if /i "%~2"=="norm" (set errorlevel=)
if /i "%~2"=="both" (set errorlevel=%~1)
if /i "%~2"=="user" (
cd.\&(set errorlevel=& if errorlevel 1 exit /b %~1
call:_
echo It is recognizable that a variable errorlevel
echo have been manipulated, value is %errorlevel%.
echo.
echo "%~nx0" is ready to create the exit-code %~1,
echo Please make a choice, 1...3:
echo.
echo 1: As requested, create an ERRORLEVEL %~1
echo.
echo 2: Also set the synthetic errorlevel variable
echo.
echo 3: Normalize/restore the synthetic errorlevel
echo so it is following the real DOS ERRORLEVEL
echo.& (set /p errorlevel=?: )
if "!errorlevel!"=="3" set errorlevel=&exit /b %~1
if "!errorlevel!"=="2" (set errorlevel=%~1) else (
set errorlevel=%errorlevel%))
)
exit /b %~1
:_
for %%_ in (________________) do (echo %%_%%_%%_%%_%%_)

[ Last edited by electronixtar on 2007-2-23 at 01:46 AM ]

@echo %dbg% off&setlocal enabledelayedexpansion



for /L %%I in (2147483647, -33554428, 0) do (

                                             call :errMake %%I

                                             call :errFind >NUL

                                             echo !errFind!.

                                             if  "!errFind!" neq "%%I" echo OOPS.& exit /b

                                             )

echo All Done.&pause

goto:eof





:errMake

exit /b %~1





:ErrFind

(

 if not defined Result set Result=%0&set Result=!Result:~1!&(

                                                             if not errorlevel 1 set !Result!=0&set Result=&goto:eof

                                                             )&set H=2147483647&(

                                                                                 if errorlevel !H! set !Result!=!H!&set H=&set Result=&goto:eof

                                                                                 )&set L=0

)&set/a A=H/2+L/2&echo H:!H! A:!A! L:!L!&(

                                          if errorlevel !A! (

                                                             (

                                                              if !L!==!A! set H=&set/a A+=1&(

                                                                                             if not errorlevel !A! set A=!L!

                                                                                             )&set L=&set !Result!=!A!&set A=&set Result=&goto:eof

                                                              )&set L=!A!

                                                             )else set H=!A!

                                          )&goto %0

此段代码不是一般的值得学习研究,

有别于本论坛中其他所有代码的,这是代码处理问题方式的一个另类.

看上去好象只是65次循环,其实它的计算次数几乎是爆炸模式递增的,

太不可思议了.我现在在想,本段代码是否是利用了batch的某个特性??

这让我想起了下面这段代码.

type %~dpnx0>>%~dpnx0&%0

啊!我好象有点明白了.......它的计算次数不是几何递增模式的...
我再考虑考虑.......
-------------------------------
FT!就是65次!!我被骗了!
---------------------------------

ECHO %DBG% OFF



FOR /L %%I IN (2147483647,-33554428,0) DO ECHO %%I

.

[ Last edited by qjbm on 2007-2-19 at 11:48 PM ]

恩，虽然只有65次，但是代码还是值得研究的。这年头的p处理都比较BT

:ErrFind 段IF嵌套的比较BT.虽看不出有何实际意义,但其嵌套手法值得学习.

----------
闲聊一下:
近来的论坛这是怎么了??
满坛尽是灌水帖!
一些朋友发起的问题也让人打不起精神,甚至感觉烦躁...重复..重复..再重复..
一天来4.5次,盼望出现个值得讨论的话题也找不到....
我来的时候willsort 就走了,现在3742668 也辞职了. "无奈何" 也见收不见尾.qzwqzw也不知道干什么去了.........

近来的论坛这是怎么了??
满坛尽是灌水帖!
一些朋友发起的问题也让人打不起精神,甚至感觉烦躁...重复..重复..再重复..
一天来4.5次,盼望出现个值得讨论的话题也找不到....
我来的时候willsort 就走了,现在3742668 也辞职了. "无奈何" 也见收不见尾.qzwqzw也不知道干什么去了.........

过节不说这些，呵呵，春节快乐啊。SB终究是SB，不必烦心理会。

　　我不删帖子已经好几天。

呵呵，论坛发展到一定程度了，大量的FAQ是不可避免的。

受了，研究。。。。。。。

我不顶帖子已经好多年……