将 List<String^> 从 C++ 传递到 C#
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Passing a List<String^> from c++ to C#
提问by Jan
Not that experienced with c++, so requesting some help here. What I got is a .net dll and I'm writing a wrapper, so that the .net dll can be used later in c++ and vb6 projects.
对 C++ 没有经验，所以在这里请求一些帮助。我得到的是一个 .net dll，我正在编写一个包装器，以便稍后可以在 c++ 和 vb6 项目中使用 .net dll。
My code so far:
到目前为止我的代码：
c# class I want to call:
我想调用的 c# 类：
public class App
{
public App(int programKey, List<string> filePaths)
{
//Do something
}
}
my c++ project:
我的 C++ 项目：
static int m_programKey;
static vector<std::string> m_fileNames;
void __stdcall TicketReportAPI::TrStart(int iProgramKey)
{
m_programKey = iProgramKey;
};
void __stdcall TicketReportAPI::TrAddFile(const char* cFileName)
{
string filename(cFileName);
m_fileNames.push_back(filename);
}
void __stdcall TicketReportAPI::TrOpenDialog()
{
if(m_fileNames.size()> 0)
{
List<String^> list = gcnew List<String^>();
for(int index = 0; index < m_fileNames.size(); index++)
{
std::string Model(m_fileNames[index]);
String^ sharpString = gcnew String(Model.c_str());
list.Add(gcnew String(sharpString));
}
App^ app = gcnew App(m_programKey, list);
}
else
App^ app = gcnew App(m_programKey);
}
If I'm trying to compile the c++ project I get following error:
如果我试图编译 C++ 项目，我会收到以下错误：
App(int,System::Collections::Generic::List ^)': Conversion from 'System::Collections::Generic::List' to 'System::Collections::Generic::List ^' not possible
App(int,System::Collections::Generic::List ^)'：从 'System::Collections::Generic::List' 到 'System::Collections::Generic::List ^' 的转换是不可能的
Is it possible to pass a managed List from c++ to .net c#? If not, what do you guys suggest me to pass a string array to my c# assembly?
是否可以将托管列表从 c++ 传递到 .net c#？如果没有，你们有什么建议我将字符串数组传递给我的 C# 程序集？
Every help is appreciated, Thanks in advance.
感谢每一个帮助，提前致谢。
采纳答案by David Yaw
You're missing a ^.
你缺少一个^.
List<String^>^ list = gcnew List<String^>();
^-- right here
You'll also need to switch list.Addto list->Add.
您还需要切换list.Add到list->Add.
You're using gcnew, which is how you create something on the managed heap, and the resulting type is a managed handle, ^. This is roughly equivalent to using newto create an object on the unmanaged heap, and the resulting type is a pointer, *.
您正在使用gcnew，这是您在托管堆上创建内容的方式，结果类型是托管句柄^. 这大致相当于用于new在非托管堆上创建对象，结果类型是一个指针，*。
Declaring a local variable of type List<String^>(without the ^) is valid C++/CLI: It makes the local variable use stack semantics. There's no C# equivalent to that variable type, so most of the .Net library doesn't work completely with it: For example, there's no copy constructors to deal with assignment to variables without the ^. All of the managed APIs expect parameters with types that have the ^, so most times, you'll want to use that for your local variables.
声明类型为List<String^>（不带^）的局部变量是有效的 C++/CLI：它使局部变量使用堆栈语义。没有与该变量类型等效的 C#，因此大多数 .Net 库不能完全使用它：例如，没有复制构造函数来处理没有^. 所有托管 API 都希望参数的类型具有^，因此大多数情况下，您希望将其用于本地变量。
Important note: Everything in this answer applies to reference types in .Net (which are declared in C# as class, or in C++/CLI as ref classor ref struct). It does not apply to value types (C# struct, C++/CLI value classor value struct). Value types (such as int, float, DateTime, etc) are always declared & passed without the ^.
重要说明：此答案中的所有内容都适用于 .Net 中的引用类型（在 C# 中声明为class，或在 C++/CLI 中声明为ref class或ref struct）。它不适用于值类型（C# struct、C++/CLIvalue class或value struct）。值类型（如int，float，DateTime，等）总是宣称与没有通过^。
