Batch add string before filename

Question

I'm working on a Windows batch file and I need to change name of files in current direcotry.

I have these files:

file1.txt
file2.txt
file3.txt

and I need to add string "REG~" before each filename like this

REG~file1.txt
REG~file2.txt
REG~file3.txt

Thank you.

Answer 1

@echo off    
SETLOCAL ENABLEDELAYEDEXPANSION    
SET old=file  
SET new=REG~file   
for /f "tokens=*" %%f in ('dir /b *.txt') do (    
    SET newname=%%f    
    SET newname=!newname:%old%=%new%!    
move "%%f" "!newname!"    
)

What this does is it loops over all .txt files in the folder where the batch file is located and replaces the file with December inside the filenames.