Count selected files, insert appropriate number within filename?

Question

Hi all. Appreciate any help you can provide. I need a script that you can run on a selection of files within a folder and insert the appropriate number of the file, inside the file after the photo ID number.
For example I have a group of photos that are like...
C00013_Filename
C00013_Filename 2
C00013_Filename 3
I would like to select these files and have the script count the number of files from the top down and then insert the correct 2-digit count number after underscore. For example...
C0001301Filename
C0001302Filename 2
C0001303Filename 3
It might even be useful to have the script ask where to start the count, for example if I already have several C00013 images number in a folder the script would ask if I wanted to start the numbering with 3, 4, 5, etc... (since the folder of files may already contain sequentially numbered files).
Thanks in advance!

Answer 1

This should do what you want for up to 99 files at a time:
<pre style="
font-family: Monaco, 'Courier New', Courier, monospace;
font-size: 10px;
margin: 0px;
padding: 5px;
border: 1px solid #000000;
width: 720px;
color: #000000;
background-color: #FFDDFF;
overflow: auto;">
tell application "Finder"
set fileList to selection
if (length of fileList) is greater than 99 then
display dialog "Select fewer than 100 files" with icon stop
else
set fileNumber to (text returned of (display dialog "Start numbering files at" default answer "1" with icon caution)) as integer
repeat with theFile in fileList
set numberText to fileNumber as text
if length of numberText is 1 then
set numberText to "0" & numberText
end if
set oldName to name of theFile
set newName to (text 1 thru 7 of oldName) & numberText & "_" & (text 8 thru end of oldName)
set name of theFile to newName
set fileNumber to fileNumber + 1
end repeat
end if
end tell </pre>