标题: [已结]如何读取文本文件开头的若干行 [打印本页]
作者: yyying67 时间: 2008-12-4 22:12 标题: [已结]如何读取文本文件开头的若干行
如何读取文本文件开头的若干行
[ Last edited by HAT on 2008-12-5 at 22:55 ]
作者: tireless 时间: 2008-12-4 23:46
例如要取前 3 行，有以下方法：
1、碰到第 3 行的内容就停止：
@echo off
for /f "delims=" %%a in (a.txt) do (
echo.%%a
if "%%a"=="第 3 行的内容" goto out
)
:out
pause
2、每读取一行内容，变量 n 的值加 1，当 n=3，即已经读取了 3 行，就停止：for /f "delims=" %%a in (a.txt) do (
echo.%%a
if "%%a"=="第 3 行的内容" goto out
)
:out
pause
@echo off & setlocal EnableDelayedExpansion
for /f "delims=" %%a in (a.txt) do (
echo.%%a
set /a n+=1 & if !n!==3 goto out
)
:out
pause
如果要处理空行：for /f "delims=" %%a in (a.txt) do (
echo.%%a
set /a n+=1 & if !n!==3 goto out
)
:out
pause
@echo off
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* a.txt') do (
echo.%%b
if %%a==3 goto out
)
:out
pause
[ Last edited by tireless on 2008-12-5 at 11:20 ]for /f "tokens=1,* delims=:" %%a in ('findstr /n .* a.txt') do (
echo.%%b
if %%a==3 goto out
)
:out
pause
作者: HAT 时间: 2008-12-5 09:47
差不多两年前，lxmxn 斑竹给出的代码：
http://www.cn-dos.net/forum/viewthread.php?tid=28639
作者: wangff 时间: 2008-12-5 13:13
请教tireless: 是否在双for中不能用goto提前跳出里边的for?
以下代码只执行一次循环
@echo off
for /r %%i in (*.txt) do (
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %%~si') do (
echo.%%b
if %%a==3 goto out
)
:out
pause
)
如果是怎改?for /r %%i in (*.txt) do (
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %%~si') do (
echo.%%b
if %%a==3 goto out
)
:out
pause
)
[ Last edited by wangff on 2008-12-5 at 13:16 ]
作者: tireless 时间: 2008-12-5 13:41 标题: RE 4 楼
@echo off
for %%i in (*.txt) do CALL :3 "%%i"
PAUSE & EXIT /B
:3
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %~s1') do (
echo.%%b
if %%a==3 goto :EOF
)
for %%i in (*.txt) do CALL :3 "%%i"
PAUSE & EXIT /B
:3
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %~s1') do (
echo.%%b
if %%a==3 goto :EOF
)
作者: wangff 时间: 2008-12-5 14:13
谢谢tireless!
但还有问题:遇到两个大的txt(几兆)后按任意键就不再往下执行!
@echo off
for %%i in (*.txt) do CALL :3 "%%i"
exit/b
:3
echo.%1
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %~s1') do (
echo.%%b
if %%a==10 (
pause
goto :EOF
)
)
不好意思,是我漏了exit/bfor %%i in (*.txt) do CALL :3 "%%i"
exit/b
:3
echo.%1
for /f "tokens=1,* delims=:" %%a in ('findstr /n .* %~s1') do (
echo.%%b
if %%a==10 (
pause
goto :EOF
)
)
[ Last edited by wangff on 2008-12-5 at 14:20 ]
作者: yyying67 时间: 2008-12-5 22:37
谢谢各位!
努力学习中.