Open explorer, select file from batch file

select.bat

@echo off
set filename=%1
set "strToMeasure=%CD%"
call :strLen strToMeasure strlen
@REM echo.String is %strlen% characters long

call :filePath %strlen% %filename%
exit /b

@REM methods stolen to get string length
@REM https://stackoverflow.com/a/17352941
:strLen
setlocal enabledelayedexpansion
:strLen_Loop
 if not "!%1:~%len%!"=="" set /A len+=1 & goto :strLen_Loop
(endlocal & set %2=%len%)
goto :eof

:filePath
if("%1"==3) (set FILEPATH="%CD%%filename%") else (set FILEPATH="%CD%\%filename%")
echo.FILEPATH=%FILEPATH%

explorer.exe /select, %FILEPATH%
explorer.exe /select, %FILEPATH%
goto :eof

I have this file in a folder added to path (environment variable), then to use it just do
select.bat filename
(Note you must be 'cd'd in the folder with the filename