Re: VC++2008 and vector exception - not caught

From:

Frank S <OldGrouch@community.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Sat, 19 Jul 2008 19:09:01 -0500

Message-ID:

<OdFkRzf6IHA.2060@TK2MSFTNGP02.phx.gbl>

Thank you for the help Alf.

I found that:

v.at(44) = 22;

throws an exception as you suggested, and

v[44] = 22;

does not (although in debug builds the error is reported).

Thanks again,

Frank

Alf P. Steinbach wrote:

* Frank S:

With some test code similar to that below, I can't seem to catch
the exception that is thrown on the v1[44]... line.

You're not guaranteed that there will be an exception, just Undefined
Behavior (which might do anything or nothing).

What should I check to solve this problem? (I am using a mixture of
MFC and STL.)

As I recall there is, as you imply, a Visual C++ option to get automatic
checking also for operator[] -- if so then it's presumably documented.

However, why don't you instead make that explicit in the code, and write

v.at(44) = 22;

Then, for a standard-conforming compiler, you get a std::something
exception derived from std::exception.

    vector<int> v1;
    try
    {
        v1[44] = 22;
    }
    catch(std::exception e)

For efficiency, safety, and not the least not making other programmers
waste time on figuring out "why did he do /that/", consider catching in
the idiomatic way, by reference to const:

catch( std::exception const& e )

    {
        e.what();
        e.what();
    }

Cheers, & hth.,

- Alf

--
Frank