__declspec（dllexport）的::矢量<标准::字符串> [英] __declspec(dllexport) ::vector<std::string>

问题描述

我一直在试图找出如何从C ++ DLL到C＃应用程序返回一个字符串数组，但我被困在如何做到这一点，或找到一个非常基本的水平的文章。

I've been trying to work out how to return an array of strings from a c++ dll to a c# application but am stuck on how to do this or find an article at a very basic level.

假设我有下面的代码。如何解决粗体显示的行：

Suppose I have the code below. How do I fix the bolded line:

extern "C" {
    __declspec(dllexport) int GetANumber();

//unsure on this line:
    **__declspec(dllexport) ::vector<std::string> ListDevices();**

}

extern::vector<std::string> GetStrings()
{
    vector<string> seqs;
    return seqs;
}

extern int GetANumber()
{
    return 27;
}

感谢

thanks

马特

推荐答案

您可以使用COM自动化的SAFEARRAY 类型，即使没有做满COM（没有对象，没有阶级，没有接口，TLB不，没有注册表等），只需用DLL出口，如

You could use the COM Automation SAFEARRAY type, even without doing full COM (no object, no class, no interface, no TLB, no registry, etc.), just with DLL exports, as .NET supports it natively with P/Invoke, something like this:

C ++：

extern "C" __declspec(dllexport) LPSAFEARRAY ListDevices();

LPSAFEARRAY ListDevices()
{
    std::vector<std::string> v;
    v.push_back("hello world 1");
    v.push_back("hello world 2");
    v.push_back("hello world 3");

    CComSafeArray<BSTR> a(v.size()); // cool ATL helper that requires atlsafe.h

    std::vector<std::string>::const_iterator it;
    int i = 0;
    for (it = v.begin(); it != v.end(); ++it, ++i)
    {
        // note: you could also use std::wstring instead and avoid A2W conversion
        a.SetAt(i, A2BSTR_EX((*it).c_str()), FALSE);
    }
    return a.Detach();
}

C＃：

C#:

static void Main(string[] args)
{ 
    foreach(string s in ListDevices())
    {
        Console.WriteLine(s);
    }
}


[DllImport("MyUnmanaged.dll")]
[return: MarshalAs(UnmanagedType.SafeArray)] 
private extern static string[] ListDevices();

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