Re: C++/CLI - How to convert List<T> to vector<T>

From:

"Ben Voigt [C++ MVP]" <bvoigt@newsgroup.nospam>

Newsgroups:

microsoft.public.vc.language

Date:

Mon, 28 Sep 2009 11:29:32 -0500

Message-ID:

<F9A54F88-2823-4562-802B-1C480D0D1023@microsoft.com>

"JohnR" <_no_spam@_no_spam.com> wrote in message
news:#1hpNBEQKHA.1268@TK2MSFTNGP04.phx.gbl...

Hi there,

I'm new to C++/CLI but very experierced in both C++ and .NET. Can someone
show me the basic syntax for converting a List<T> to vector<T> (or more
generally, any .NET generic to its C++ template equivalent). For now I'm
looking for a template with a signature similar to the following (note
however that "T" would also need to be converted presumably so a template
arg and a generic arg may be required). Thanks in advance.

std::vector<T> marshal_as(System::Collections::Generic::List<T> ^ const &
list)

Returning vector by value is going to have really bad performance unless you
have the move optimization.

For types which have dual managed/native identity (i.e. built-in numeric
types), something like:

template<typename T>
std::vector<T> marshal_as(System::Collections::Generic::ICollection<T>^
list)
{
    if (list == nullptr) throw gcnew ArgumentNullException(L"list");
    std::vector<T> result(list->Count);
    for each (T& elem in list)
        result.push_back(elem);
    return result;
}

More generally, something like:

template<typename T>
generic<typename S>
std::vector<T> marshal_as(System::Collections::Generic::ICollection<S>^
list)
{
    if (list == nullptr) throw gcnew ArgumentNullException(L"list");
    std::vector<T> result(list->Count);
    for each (S& elem in list)
        result.push_back(marshal_as<T>(elem));
    return result;
}

Not compile-tested.