Rename all files in folder to uppercase with batch

Question

Is there a way to rename all files in a specific folder to uppercase with batch file?
I found this code. But it renames files to lowercase. How to modify it to rename to uppercase instead?

for /f "Tokens=*" %f in ('dir /l/b/a-d') do (rename "%f" "%f")

Answer 1

@echo off
setlocal enableDelayedExpansion

pushd c:\some_dir

for %%f in (*) do (
   set "filename=%%~f"

   for %%A in (A B C D E F G H I J K L M N O P Q R S T U V W X Y Z) do (
      set "filename=!filename:%%A=%%A!"
   )
    ren "%%f" "!filename!" >nul 2>&1
)
endlocal

Answer 2

This will put the extension to upper case as well.... Which was a problem for me... So this how I "kept" extension as lower case...

@echo off
setlocal enableDelayedExpansion

pushd "\...\PATH_TO_FOLDER\"

for %%f in (*) do (
   set "filename=%%~f"

   for %%A in (A B C D E F G H I J K L M N O P Q R S T U V W X Y Z) do (
      set "filename=!filename:%%A=%%A!"
   )
    ren "%%f" "!filename!" >nul 2>&1
)

for /r "\...\PATH_TO_FOLDER\" %%G in (*.PDF) do ren "%%~G" *.pdf

endlocal

replace \...\PATH_TO_FOLDER\ with your path and .PDF/.pdf with your file extention as needed.