Fit

@echo off&setlocal enabledelayedexpansion
set my=%~nx0

for /f %%i in ('dir /b /a-d') do (
if not "%%i"=="%my%" (
call:StrLen %%~ni
echo ren %%i !name!%%~xi)
)

pause

:StrLen
set /a len=0
set str=%1
set name=
for /l %%i in (0,1,50) do (
if not "!str:~%%i,1!"=="" (
set name=!name!!str:~%%i,1!飞
set /a len+=1)else (goto:eof)
)