how to rename files in a pair with a script - windows

Question

I have 10 pdf files in a folder and im trying to find a way to rename them as pairs using a script for it to look like something like this
file131.pdf = order_receipt_1000.pdf
file304.pdf = invoice_1000.pdf
file542.pdf = order_receipt_1001.pdf
file194.pdf = invoice_1001.pdf
and so on for the next 8 ones

Answer 1

maybe this gives you a good starting point. The language is Autoit. (www.autoitscript.com)
Currently the script looks into the folder where it is saved for *pdf files. Then an new array with the files found is created an the second column contains the time when the file has been created. After that the last For-loop renames the files in chunks of two files each.
#include <Array.au3>
#include <File.au3>
#include <MsgBoxConstants.au3>
Example()
Func Example()
Local $aFileList = _FileListToArray(#ScriptDir, '*.pdf', Default, True) ; change #scriptDir to the path you need
If #error = 1 Then
MsgBox($MB_SYSTEMMODAL, "", "Path was invalid.")
Exit
EndIf
If #error = 4 Then
MsgBox($MB_SYSTEMMODAL, "", "No file(s) were found.")
Exit
EndIf
_ArrayDisplay($aFileList, "Files FOUND")
Local $a[UBound($aFileList)][2]
For $i = 0 To UBound($aFileList) - 1
$a[$i][0] = $aFileList[$i]
$a[$i][1] = FileGetTime($aFileList[$i], $FT_CREATED, $FT_STRING) ; change FT_CREATED to what you need (created, modified, ...)
Next
_ArraySort($a, 0, 0, 0, 1)
_ArrayDisplay($a, "Sorted FileList")
Local $startcount = 1000, $y = 0
For $i = 1 To UBound($a) - 1 Step 2
FileMove($a[$i][0], 'order_receipt_' & $startcount + $y & '.pdf')
FileMove($a[$i + 1][0], 'invoice_' & $startcount + $y & '.pdf')
$y += 1
Next
EndFunc ;==>Example