大家好：统计指定长度的行，我写的代码感觉有问题，但是找不出原因，请大家帮忙看下，谢谢
@echo off & setlocal enabledelayedexpansion
set /p bb=请输入行字符数：
for /f %%a in (d:\test.txt) do (
set line=%%a
set var=%bb%
for /l %%m in (0 1 100) do (
set line1=%%m
if "!line:~!line1!,1!"=="" (
if !var!==!line1! (
echo !line!
set line=
))))
pause
@echo off & setlocal enabledelayedexpansion
set /p bb=请输入行字符数：
for /f %%a in (d:\test.txt) do (
set line=%%a
set var=%bb%
for /l %%m in (0 1 100) do (
set line1=%%m
if "!line:~!line1!,1!"=="" (
if !var!==!line1! (
echo !line!
set line=
))))
pause