command line - Batch to Create a Subdirectory for Each file in Main Directory

I have a batch file that loops through a folder, inserting a line of text into each CSV in a folder and generating a file that counts the lines of each file.

I want to also generate a subdirectory in the main folder for each CSV file, without including the ".csv" extension. The code below seems like it should work, (it works when I isolate the three lines to their own bat file!) but in the loop, it returns the same value for the folder name each iteration of the loop. How do I make the dirname variable update with the current value?

copy NUL count.txt
for %%f in (*.csv) do (
    setlocal EnableDelayedExpansion
    set "cmd=findstr /R /N "^^" %%f | find /C ":""
        for /f %%a in ('!cmd!') do set number=%%a
        echo %%f   !number!>>count.txt
        SET filename=%%f
        SET dirname=%filename:~0,13%
        mkdir %dirname%
    type header.txt >%%f.new
    type %%f >>%%f.new
    move /y %%f.new %%f
 )

Answer

In the loop, it returns the same value for the folder name each iteration of the loop

SET dirname=%filename:~0,13%

You need to use delayed expansion just like you did for number:

SET dirname=!filename:~0,13!

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