@echo off
setlocal enabledelayedexpansion
echo 请问你要每几行合并成一行，请输入数字,回车确定！
@set /p m=
for /f "tokens=*" %%i in (%*) do (
set /a hangn+=1
set /a n+=1
set line=!line!%%i
if !n! equ !m! (
echo !line!>>result.txt
set line=
set /a n=0
)
)
rem 以下代码用于处理剩下的行
set /a t=!hangn!%%!m!
if !t! equ 0 goto end
echo !line!>>result.txt
:end
endlocal

@echo off
    setlocal enabledelayedexpansion
rem 下面的文件名若包含空格注意加引号
    set file=a.txt
    for /f "delims=: tokens=1*" %%i in ('findstr /n .* %file%') do set num=%%i && set "%%i=%%j"
    
    echo 显示全部:
    for /l %%i in (1,1,%num%) do echo,!%%i!
    pause

    echo 显示单数行:
    for /l %%i in (1,2,%num%) do echo,!%%i!
    pause

    echo 显示双数行:
    set "num_ex="
    set /a num_ex=%num% + 1
    for /l %%i in (2,2,%num_ex%) do echo,!%%i!
    pause

    echo 每两行合并:
    set str=
    for /l %%i in (1,1,%num%) do (
        if defined str (echo,!str!!%%i!&&set "str="
                       ) else (
                               set "str=!%%i!"
                               )
    )
    echo,!str! && set "str="
    pause

    echo 显示前10行:
    for /l %%i in (1,1,10) do if defined %%i echo,!%%i!
    pause
exit /b 0