Question

以下程序是 ms dos 的批处理文件,

Answer 1

@echo off setlocal enabledelayedexpansion//关闭显示并启用变量延迟,启用本地变量

:: %1 -- String//字符串//::标注%1~%6是调用程序外部的参数

:: %2 -- Filename//文件名

:: %3 -- Environment variable//环境变量

:: %4 -- Start address//开始地址

:: %5 -- get length//获取长度

:: %6 -- which line that include string to get, default = 1 (first line include %1) ,-1 means last one//获取字符串的行,默认为1,-1表示最后一行

if %5@==@ goto usage//如果%5参数为空,就跳转到:usage处运行

Set %3=//设置%3为空字符

Set Number_Of_Found_Word=-1//设置Number_Of_Found_Word为-1

if "%6"=="" ( set Expect_Found_Time=1 ) ELSE ( set Expect_Found_Time=%6 )

//如果%6为空,则Expect_Found_Time=1,否则Expect_Found_Time为%6的值

For /F "skip=1 usebackq delims=" %%a IN (`find "%~1" %2`) Do call :set_env "%%a" %*

//for语句你需要好好了解一下,功能很强,需要多练.skip=1—跳过第一行进行操作,usebackq是增强型参数,没有它的话find语句只需用单引号括起来,用了之后需用`；delims是分隔符,默认是空格什么的.find "%~1" %2是遍历的数据集,在文件名为%2的文件中查找"%~1"这个字符串,如果查到了就执行do语句,这里是调用本程序的:set_env语句块,%*指从第一个参数到最后一个参数

endlocal//结束本地变量,这个概念意思比如前面我定义了t这个变量,后来我再setlocal和endlocal里面重新定义了t,最后我还想使用先前定义的t,那么endlocal之后用的就是原来的了

call out.bat//调用out.bat批处理

if exist out.bat del out.bat//如果存在out.bat就删除它

goto end//跳转到程序尾部,结束程序

:set_env//名为set_env的语句块

shift//这个命令还没用过,只知道一点概念,就不说了

:: skip first line , it is not content of target file//注释

set /A Number_Of_Found_Word=%Number_Of_Found_Word%+1//set /a表示进行数值运算,所以后面能用Number_Of_Found_Word=%Number_Of_Found_Word%+1,将变量Number_Of_Found_Word加1赋予自身,类似与其他语言的i++之类的

if not %Number_Of_Found_Word%==%Expect_Found_Time% if not %Expect_Found_Time%==-1

goto :eof

//如果变量不等于Expect_Found_Time,而且Expect_Found_Time不等于-1,就结束程序

set %3=%~0//将本程序名赋予参数%3,0表示本程序名称

echo set %3=!%3:%4,%5! >out.bat//这里用到了变量延迟,!%3:%4,%5!的意思是截取字符串,重定向传给out.bat

goto :eof

//下面的echo就不说了,就是显示功能

:usage

Echo -Usage:

Echo -Wjenv string filename environment_variable start_addr Length [times]

Echo -

Echo -Search "string" in "filename" ,

Echo -and get "Length" chars from the line add offset "Start_addr"

Echo -Then set to environment "environment_variable" .

Echo -

Echo -[times] is option argument to specified that get from which line that

Echo -include "string" .

Echo -1 means first time , -1 means last time.

goto :eof

:end