Batch: how to split string on uppercase letter

Question

I have a directory structure containing home directories named after the users full name (ForenameSurname), like:

/user/JohnDoe
/user/JaneDoe
/user/MobyDick

Now i want to copy the whole structure, changing ForenameSurname to "'first two letters of first name'+'surname'", resulting:

/user/JoDoe
/user/JaDoe
/user/MoDick

I know how to get substrings (~n), but how to split a string on the first capital letter? Is it possible at all using pure batch?

Answer 1

@echo off
    setlocal enableextensions enabledelayedexpansion

    set "root=%cd%\users"

    for /d %%f in ( "%root%\*" ) do (
        set "name=%%~nxf"
        for /f %%a in ("!name:~0,2!"
        ) do for /f "tokens=* delims=abcdefghijklmnopqrstuvwxyz" %%b in ("!name:~2!"
        ) do if not "%%~nxf"=="%%~a%%~b" if not exist "%root%\%%~a%%~b" (
            echo ren "%%~ff" "%%~a%%~b"
        ) else (
            echo "%%~nxf" can not be renamed to "%%~a%%~b"
        )
    )

Rename operations are only echoed to console. If the output is correct, remove the echo that prefixes the ren command.

Answer 2

Try this:

@echo off
setlocal EnableDelayedExpansion

set "upcaseLetters=ABCDEFGHIJKLMNOPQRSTUVWXYZ"

cd \user
for /D %%a in (*) do (
   call :convert name=%%a
   echo New name: !name!
)
goto :EOF


:convert
set "var=%2"
:nextChar
   set "char=%var:~2,1%"
   if "!upcaseLetters:%char%=%char%!" equ "%upcaseLetters%" goto end
   set "var=%var:~0,2%%var:~3%"
goto nextChar
:end
set "%1=%var%"
exit /B