They're trying to tokenize HTML into two arrays, one being an array of opening tags and one of closing tags, with the hope being to pairwise compare and reconcile the elements of these arrays.
The necessary clarification appears further down the page.
As for whether it's a reasonable question; as written I beg to differ, it's the opposite, since it does not convey their problem except by a very careful and nuanced reading. The proper response of the S.O. community should've been to aid the OP in clarifying their intentions and amending the question accordingly to bring focus onto their actual problem.
That is not what happened. Instead they are indeed on the receiving end of some ridicule, which is shameful, but the advice of "use a parser" would still likely have been a top answer in some fashion had the OP's scattered ancillary questions and clarifications been incorporated.
Sadly, only one correspondent of many seems to have seen fit to ask.
The necessary clarification appears further down the page.
As for whether it's a reasonable question; as written I beg to differ, it's the opposite, since it does not convey their problem except by a very careful and nuanced reading. The proper response of the S.O. community should've been to aid the OP in clarifying their intentions and amending the question accordingly to bring focus onto their actual problem.
That is not what happened. Instead they are indeed on the receiving end of some ridicule, which is shameful, but the advice of "use a parser" would still likely have been a top answer in some fashion had the OP's scattered ancillary questions and clarifications been incorporated.
Sadly, only one correspondent of many seems to have seen fit to ask.