Hello123World

@echo off
setlocal EnableDelayedExpansion
(For /f "delims=: tokens=1*" %%i in ('findstr /n ".*" a.txt') do (
	Set n=%%i
	If !n! lss 10 Set n=000!n!
	If !n! gtr 9 If !n! lss 100 Set n=00!n!
	If !n! gtr 99 If !n! lss 1000 Set n=0!n!
	echo.!n! %%j
	)
	)>aa.txt
start aa.txt
pause
复制代码

4，6楼的算法好，我这个太罗嗦了。