#include <StringConstants.au3> ; to declare the Constants of StringRegExp
#include <Array.au3> ; UDF needed for _ArrayDisplay and _ArrayConcatenate
Local $sRegex = "(?m)(?<!(base64).*)(?<![\/@#:\.])\bV\b(?![:#])"
Local $sString = "base64:= "iVBORw0KGgoAAAANSUhEUgAAAyAAAAJzCAYAAAD3HXeFAAAgAElEQVR4nOy9W3bksI4ECOp6ET2n56dn/1u8yfkgAeJJUbaryo+IUy5nSiQIUuEEFIKU7f/7f/+fTkTUeydqjah3aq0RUSNqRNQ7ddk20Oc2bnO1Rq9XJ27SO9F1XdT7a/RrjfrrRURErbXZl8z7MQZRa9ewwfvneNyutUatNXq9XkTzNb1e1K7hwzRK/TXGbtdFr//+V/pp//" & @CRLF & _
"" & @CRLF & _
"" & @CRLF & _
"base64:=+V" & @CRLF & _
"" & @CRLF & _
"V" & @CRLF & _
"" & @CRLF & _
"base64:=V" & @CRLF & _
"" & @CRLF & _
"base65 := "iVBORw0KGgoAAAANSUhEUgAAAyAAAAJzCAYAAAD3HXeFAAAgAElEQVR4nOy9W3bksI4ECOp6ET2n56dn/1u8yfkgAeJJUbaryo+IUy5nSiQIUuEEFIKU7f/7f/+fTkTUeydqjah3aq0RUSNqRNQ7ddk20Oc2bnO1Rq9XJ27SO9F1XdT7a/RrjfrrRURErbXZl8z7MQZRa9ewwfvneNyutUatNXq9XkTzNb1e1K7hwzRK/TXGbtdFr//+V/pp//Wcxv7h+4v7znnxUkjb66L+eqU2eG56Pr0T9f6i67pkH0+uUTPb2N5LrRevg5mj7OukltP06b3TdbU5fo/rx/P2E3T+9N6pXRdR72Ntrmscl3kM/Nh6XcAr8EoDv" & @CRLF & _
"" & @CRLF & _
"base65:=V"
Local $aArray = StringRegExp($sString, $sRegex, $STR_REGEXPARRAYGLOBALFULLMATCH)
Local $aFullArray[0]
For $i = 0 To UBound($aArray) -1
_ArrayConcatenate($aFullArray, $aArray[$i])
Next
$aArray = $aFullArray
; Present the entire match result
_ArrayDisplay($aArray, "Result")
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