#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "https?:\/\/\Kexample\.com"
Local $sString = "<img class="aligncenter wp-image-27283 size-large" src="http://example.com/wp-content/uploads/2017/04/image-3-1024x1024.jpeg" alt="homemade chocolate recipe" width="640" height="640" srcset="http://example.com/wp-content/uploads/2017/04/image-3-1024x1024.jpeg 1024w, http://example.com/wp-content/uploads/2017/04/image-3-300x300.jpeg 300w, http://example.com/wp-content/uploads/2017/04/image-3-768x768.jpeg 768w, http://example.com/wp-content/uploads/2017/04/image-3-696x696.jpeg 696w, http://example.com/wp-content/uploads/2017/04/image-3-1068x1068.jpeg 1068w, http://example.com/wp-content/uploads/2017/04/image-3-420x420.jpeg 420w, http://example.com/wp-content/uploads/2017/04/image-3-560x560.jpeg 560w, http://example.com/wp-content/uploads/2017/04/image-3.jpeg 1080w" sizes="(max-width: 640px) 100vw, 640px" />"
Local $sSubst = "abc.host.prov.com"
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