The search box was not found after the website was updated,where is it?

At the top, in the middle.

It's right there at the top of the page.

...Still not found,Is it browser related(My is edge)?I found "<div id="I_search">" by F12,but couldn't check it.

KaiTang wrote:
Is it browser related(My is edge)?

It doesn't seems like it. I just tested with Edge on my "work laptop" and I can clearly see the search field the same way as in other browsers.

There has been quite a lot of updates recently so perhaps you should try and see if clearing your cache makes it work.

The search listbox shows up fine on my Desktop PC's Edge.

A search with Edge seems to run better/faster than with my older version of FireFox.

Since the admin updated the look of cplusplus searches no longer show weird non-cplusplus results. Say I searched for "std::vector" I'd get a couple of links at the top of the search page about STDs. Venereal diseases. o_O

Using firefox (latest version) and doing a search (eg for std::vector), I only get 1 page of results and no obvious way of scrolling through further pages...

Using Edge I have the search toolbar in top/middle. No problem ++

Under Firefox latest version I did a search - the same than yours @seeplus :

C++ Search - "std::vector"
About 15,400 results (0.28 seconds)

The same request a few seconds after the first one :
C++ Search - "std::vector"
About 18,300 results (0.51 seconds)

It makes sense :)

Using my older version of FF I get at the bottom of the page links for at least 10 pages of search results. Same for Edge.

It looks like 10 pages is the max available, starting at the 4th page results are not directly related to std::vector, the links have a mention of std::vector.

Of course the actual search page that begins to serve up mentions of std::vector varies as to "results" tab selected. All results, Reference or Forum.