#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)(?:^\.+|(\.)\.+)"
Local $sString = "543.210.987.654.321" & @CRLF & _
"43.210.987.654.321" & @CRLF & _
"987.654...321" & @CRLF & _
"87.654...321" & @CRLF & _
"7.654...321" & @CRLF & _
"654....321" & @CRLF & _
"54....321" & @CRLF & _
"4....321" & @CRLF & _
"....321" & @CRLF & _
"21" & @CRLF & _
"1" & @CRLF & _
""
Local $sSubst = "$1"
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