【练习-044】批处理对文本内容加密

batman

&&有文本a.txt内容如下：

The Boston Evening Transcript 
　　　　 
THE READERS of the Boston Evening Transcript 
Sway in the wind like a field of ripe corn. 
　　　　 
When evening quickens faintly in the street, 
Wakening the appetites of life in some 
And to others bringing the Boston Evening Transcript, 
I mount the steps and ring the bell, turning 
Wearily, as one would turn to nod good-bye to Rochefoucauld, 
If the street were time and he at the end of the street, 
And I say, “Cousin Harriet, here is the Boston Evening Transcript. 
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要求使用批处理将原文的英文字母进行加密输出到b.txt，同时根据b.txt中的内容还原原文内容，并追加输出到b.txt，如下：

密文
srq bfxsfl qvqloli stmlxetoas 
　　　　 
srq tqmwqtx fc srq bfxsfl qvqloli stmlxetoas 
xpmg ol srq polw dozq m coqdw fc toaq eftl. 
　　　　 
prql qvqloli kjoezqlx cmolsdg ol srq xstqqs, 
pmzqloli srq maaqsosqx fc docq ol xfuq 
mlw sf fsrqtx btolioli srq bfxsfl qvqloli stmlxetoas, 
o ufjls srq xsqax mlw toli srq bqdd, sjtloli 
pqmtodg, mx flq pfjdw sjtl sf lfw iffw-bgq sf tferqcfjemjdw, 
oc srq xstqqs pqtq souq mlw rq ms srq qlw fc srq xstqqs, 
mlw o xmg, “efjxol rmttoqs, rqtq ox srq bfxsfl qvqloli stmlxetoas. 
原文
the boston evening transcript 
　　　　 
the readers of the boston evening transcript 
sway in the wind like a field of ripe corn. 
　　　　 
when evening quickens faintly in the street, 
wakening the appetites of life in some 
and to others bringing the boston evening transcript, 
i mount the steps and ring the bell, turning 
wearily, as one would turn to nod good-bye to rochefoucauld, 
if the street were time and he at the end of the street, 
and i say, “cousin harriet, here is the boston evening transcript. 
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本题满分20分，视情况加分。

batman

做本题需要用到乱序，即将字母a-z乱序后再进行赋值，不多说了，只是帮大家打开一下思路了。

batman

看来大家是怕麻烦，先公布下本人的解吧（除了逐字符法没想到合适的办法，效率上有问题）：

@echo off&setlocal enabledelayedexpansion
echo 密文：>b.txt
set "code=a b c d e f g h i j k l m n o p q r s t u v w x y z"
for %%a in (%code%) do set /a n+=1&set "_!n!=%%a"&set ".!n!=%%a"&rem 生成正常序列
for /l %%a in (1,1,26) do (
    set /a num=!random!%%26+1
    call,set "temp=%%_!num!%%"
    set "_!num!=!_%%a!"&set "_%%a=!temp!"
)&rem 乱序
for /l %%a in (1,1,26) do set "!_%%a!=!.%%a!"&set "_!.%%a!=!_%%a!"
for /f "delims=" %%a in (a.txt) do set "str=%%a"&call :lp
echo 原文：>>b.txt
for /f "skip=1 delims=" %%a in (b.txt) do if "%%a" neq "原文：" set "str=%%a"&call :lp ok
start b.txt&goto :eof
:lp
if "%1" equ "ok" set "ok=_"
:loop
set "flag="
if /i "%str:~,1%" geq "a" if /i "%str:~,1%" leq "z" set "flag=a"
if defined flag (
   set /p=!%ok%%str:~,1%!<nul>>b.txt
   ) else (
   set /p=!str:~,1!<nul>>b.txt
)
set "str=%str:~1%"
if defined str goto loop
echo.>>b.txt
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[ 本帖最后由 batman 于 2009-4-20 10:38 编辑 ]