@ECHO OFF
SETLOCAL
rem The following setting for the directory is a name
rem that I use for testing and deliberately includes spaces to make sure
rem that the process works using such names. These will need to be changed to suit your situation.

SET "sourcedir=u:\your files"

SET /a nextprefix=1

FOR /f "tokens=1delims=-" %%e IN (
 'dir /b /ad "%sourcedir%\*" '
 ) DO CALL :process "%%e"

ECHO Next prefix is %nextprefix%

GOTO :EOF

:process
SET "$=9%~1"
FOR /l %%z IN (0,1,9) DO CALL SET "$=%%$:%%z=%%"
IF DEFINED $ GOTO :eof
IF %~1 geq %nextprefix% SET /a nextprefix=%~1+1
GOTO :eof

注意，这个例程只计算下一个前缀。
列出目录，抓取-前面的名称部分，用引号引起来并传递给:process。
在:process中，用9作为传递字符串的前缀，然后删除每个数字。如果结果是字符串不为空，则字符串中存在其他字符，因此忽略它。
否则，如果字符串的值〉= current next-value，则将next-value设置为比字符串的值大1。
9作为字符串的前缀，以便字符串在最后一次替换之前不会变为空。

因此，感谢Magoo我得到了我的批处理工作。我张贴下面的编辑代码，也许有人用它。再次感谢！

@echo off

rem Codepage Einstellung auf ANSI für deutsche Umlaute
chcp 1252>nul

echo.
echo.
echo M&A Filestruktur Generator
echo Dr. Hans-Friedrich Fuge, Stand 10/01/2023
echo.
echo.


setlocal enabledelayedexpansion

rem Find the next "free" Prefix as new project number

SET /a nextprefix=1

FOR /f "tokens=1delims=-" %%e IN (
 'dir /b /ad *" '
 ) DO CALL :process "%%e"

GOTO :Neuprojekt

:process
SET "$=9%~1"
FOR /l %%z IN (0,1,9) DO CALL SET "$=%%$:%%z=%%"
IF DEFINED $ GOTO :eof
IF %~1 geq %nextprefix% SET /a nextprefix=%~1+1
GOTO :eof

:Neuprojekt
rem Ask for new project name
set /p projectname=Wie lautet das neue Projekt (idealerweise Format PROJEKTNAME-UNTERNEHMENSNAME):

rem Reject input if empty
if "%projectname%" == "" (
echo.
echo Ungültige Eingabe, es muß ein Projektname eingegeben werden.
echo.
echo.
pause
exit
)

rem Check if project name already exists as folder label
for /D %%F in (*) do (
for /F "tokens=2 delims=-" %%P in ("%%F") do (
if /I "%%P" == "%projectname%" (
echo.
echo.
echo Der Projektname exitiert bereits als %%F.
pause
exit
)
)
)

rem Create new folder with incremented Prefix and project name
md %nextprefix%-"%projectname%"
cd %nextprefix%-"%projectname%"

rem Erstellung der Unterordner Struktur

md Prozess
md Offers
md "Due diligence"
md Financials
md Legal
md alt

cd Prozess
md NDA
md IM
md MP
md "Process letter"
cd..

cd Offers
md "Indicative offer"
md "Binding offer"
cd Indicative offer
md alt
cd..
cd Binding offer
md alt
cd..
cd..

cd Due diligence
md Templates
md Research
md "Data room"
cd..

cd Financials
md Dealsheet
md Model
cd Model
md alt
cd..
md "Other financials"
cd..

cd legal
md SPA
cd SPA
md alt
cd..
md "Other legal"
cd..

echo.
echo Es wurde eine neue Projektstruktur unter %nextprefix%-"%projectname%" erstellt.
echo.
endlocal
pause