China DOS Union

It's too profound. I can't understand it!

I'll add another post. I posted the translation on the 14th floor before, but in the following floors, some people said they still couldn't understand. Considering my poor English level might cause misunderstandings, I deleted it. I'm posting it again today and ask experts to correct it.

Don't the friends who understand English see it?
It seems I have to try with my poor level, hoping to start a discussion.
Please criticize and correct but don't laugh, my skin is very thin. ^_^

This page tells everyone how to read a certain line from a text file. There are many methods to use for/f to read the content of input.txt, for example:



for /f "delims=" %%a in (input.txt) do ...



for /f "delims=" %%a in ('type input.txt') do ... 



for /f "delims=" %%a in ('more ^< input.txt') do ... 



However, only the last method (using the more command) can get consistent results in different operating systems such as Windows NT, 2000, XP and 2003. The first method cannot recognize UNICODE-encoded files, and if the input file name contains spaces, the usebackq parameter must be used. The second method, using the type command, also does not recognize UNICODE files in Windows 2000, XP and 2003 if the file does not start with a byte order mark (BOM).



In all examples, assume the content of numbers.txt is:



one

two

three

four

five

six

seven

eight

nine

ten



Display the first line



This example outputs one.



@echo off & setlocal ENABLEEXTENSIONS

set "first="

for /f "delims=" %%a in ('more ^< numbers.txt') do (

  if not defined first set first=%%a

)

echo/%first%



Display the first few lines



This example outputs one, two and three.



@echo off & setlocal ENABLEEXTENSIONS

set "lines=3"

set i=-1

set "ok=" 

for /f "delims=" %%a in ('more ^< numbers.txt') do (

  set/a i+=1 & for /f %%z in ('echo/%%i%%') do (

    if "%%z"=="%lines%" set ok=1

  )

  if not defined ok echo/%%a

)



Display the last line



This example outputs ten.



@echo off & setlocal ENABLEEXTENSIONS

for /f "delims=" %%a in ('more ^< numbers.txt') do set "last=%%a"

echo/%last%



Display the last few lines



This example outputs nine and ten.



@echo off & setlocal ENABLEEXTENSIONS

set "lines=2"

for /f %%a in ('find/c /v "" ^< numbers.txt') do set/a skip=%%a-lines

for /f "delims=" %%a in ('more/e +%skip% ^< numbers.txt') do (

  echo/%%a

)



Display the nth line



This example outputs three. Note that the /e parameter of more is used here to skip the specified number of lines, and when used with for/f, it will fail if the value is less than 1.





@echo off & setlocal ENABLEEXTENSIONS

set LineNo=3

set "line="

set/a LineNo-=1

for /f "delims=" %%a in ('more/e +%LineNo% ^< numbers.txt') do (

  if not defined line set "line=%%a"

)

echo/%line%



Display the nth line plus X lines



This example outputs five and six.



@echo off & setlocal ENABLEEXTENSIONS

set start=5

set "lines=2"

set/a i=-1,start-=1

set "ok=" 

for /f "delims=" %%a in ('more/e +%start% ^< numbers.txt') do (

  set/a i+=1 & for /f %%z in ('echo/%%i%%') do (

    if "%%z"=="%lines%" set ok=1

  )

  if not defined ok echo/%%a

) 

Encountering lines like this is ineffective??

<td width=45 align=center rowspan=2>3</td>
<td width=83 align=center rowspan=2>02.I</td> <!-- @T -->

Now you can use bat to do RSS.