#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)([+]*)([0-9]+)(([,])([0-9]+))*"
Local $sString = "+000123,456" & @CRLF & _
"+123" & @CRLF & _
"000123,456" & @CRLF & _
"123" & @CRLF & _
"+123.45" & @CRLF & _
"-123,45"
Local $sSubst = "$2${3:+.$5:}"
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm