Windows script to delete everything but image file extensions - powershell

Question

I want to create a script on Windows 7 to delete everything in a directory that is not a picture.
So
for all files in directory X
if file y does not have extension in (.png, .gif, .jpeg)
delete y
end
that's it
how can I find or create such a script
mind you, some pictures are important, so this script has to work correctly :) I don't think I should be experimenting here, and even if I tested my own script on a small directory with experimental files, I am not confident that I should try it.
I have this code as suggested:
::extensions are delimited with space // filename is del_stuff.bat
set "extensions_list=.png .gif .jpeg .bmp .jpg "
pushd "C:\Users\denman\Desktop\xxx\"
for /f "delims=" %%f in ('dir /b ^|findstr /i /e /v "%extensions_list%" ') do (
echo del /q /f "%%~f"
)
popd
But I get this error:

Answer 1

Using Powershell, you can get the list of files you need with something like this:
Get-ChildItem | where {!$_.PsIsContainer -and !(#(".png",".gif",".jpeg") -contains $_.Extension) }
I left the Delete command to you, make sure the list returns correct results before you do it.

Answer 2

#echo off
::extensions are delimited with space
set "extensions_list=.png .gif .jpeg "
pushd "C:\Directory_with_pictures" && (
for /f "delims=" %%f in ('dir /b /a-d ^|findstr /i /e /v "%extensions_list%" ') do (
echo del /q /f "%%~f"
)
popd
)
The 'echo' is to verify the result .remove the echo to activate deletion.And change "C:\Directory_with_pictures" with the actual path.
EDIT testing the script:
#echo off
md test_dir>nul 2>&1
echo #>test_dir\t1.png
echo #>test_dir\t1.txt
echo #>test_dir\t1.tst
echo #>test_dir\t1.jpg
echo #>test_dir\t1.gif
echo #>test_dir\t2.png
echo #>test_dir\t2.txt
echo #>test_dir\t2.tst
echo #>test_dir\t2.jpg
echo #>test_dir\t2.gif
echo -- before deleting--
dir /b .\test_dir\*
echo(
echo(
::extensions are delimited with space
set "extensions_list=.png .gif .jpeg .jpg"
pushd "test_dir"
for /f "delims=" %%f in ('dir /b ^|findstr /i /e /v "%extensions_list%" ') do (
del /q /f "%%~f"
)
popd
echo -- after deleting --
dir /b .\test_dir\*
Output:
-- before deleting--
t1.gif
t1.jpg
t1.png
t1.tst
t1.txt
t2.gif
t2.jpg
t2.png
t2.tst
t2.txt
-- after deleting --
t1.gif
t1.jpg
t1.png
t2.gif
t2.jpg
t2.png