RosettaCodeData/Task/Longest-common-substring/AutoHotkey/longest-common-substring-3.ahk

LCS(a, b){
	while pos := RegExMatch(a "`n" b, "(.+)(?=.*\R.*\1)", m, pos?pos+StrLen(m):1)
		res := StrLen(res) > StrLen(m1) ? res : m1
	return res
}