#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "https:\/\/gyazo.com\/([0-9A-Za-z]{1,32})"
Local $sString = "https://gyazo.com/683fd0d45622162038ee0aed541c45e4"
Local $sSubst = "https://i.gyazo.com/$1.png"
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