#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "\\\\|\\\*|\*\*((?:\\\\|\\\*\*|\*(?!\*)|[\S\s])*?)\*\*"
Local $sString = "**bold**" & @CRLF & _
"**foo * bar **" & @CRLF & _
"**foo \** bar**" & @CRLF & _
"**foo \\** bar** **" & @CRLF & _
"\**bold** **" & @CRLF & _
"\\**bold**" & @CRLF & _
""
Local $sSubst = "$0\t\t\t<strong>$1<strong>"
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