#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(\#)([a-zA_Z0-9]*)(\#)(\s{1})(.*)\n{1}(\s{2})([a-zA_Z0-9]*)(\s{3})(.*)"
Local $sString = "#1# OPTION 1" & @CRLF & _
" 2 OPTION 2" & @CRLF & _
" 3 OPTION 3" & @CRLF & _
" 4 OPTION 4" & @CRLF & _
" 5 OPTION 5" & @CRLF & _
" 6 OPTION 6" & @CRLF & _
" 7 OPTION 7" & @CRLF & _
" 8 OPTION 8" & @CRLF & _
" 9 OPTION 9" & @CRLF & _
" 10 OPTION 10" & @CRLF & _
" 100 OPTION 100" & @CRLF & _
" 1000 OPTION 1000" & @CRLF & _
"" & @CRLF & _
"[REPLACEALL](\#)([a-zA_Z0-9]*)(\#)(\s{1})(.*)\n{1}(\s{2})([a-zA_Z0-9]*)(\s{3})(.*)[WITH]$6$2$8$5" & @CRLF & _
"#$7#$4$9"
Local $sSubst = "$6$2$8$5\n#$7#$4$9"
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