System::String^ 到 TCHAR*

Question

我有一个类，它收集给定文件夹的 .txt 文件的所有路径并将它们存储到向量中。我使用的大多数功能都需要使用 TCHAR* 来获取/设置当前目录等。

类如下所示：

typedef std::basic_string<TCHAR> tstring;
class folderManager
{
private:
    TCHAR searchTemplate[MAX_PATH]; 
    TCHAR directory[MAX_PATH];          

    WIN32_FIND_DATA ffd;
    HANDLE hFind;        

    vector<tstring> folderCatalog; 
    vector<tstring> fileNames;     

    bool succeeded; 

public:
    // get/set methods and so on...
};
// Changed TCHAR* dir to tstring dir
void folderManager::setDirectory(tstring dir)
{
    HANDLE hFind = NULL;
    succeeded = false;

    folderCatalog.clear();
    fileNames.clear();
    // Added .c_str()
    SetCurrentDirectory(dir.c_str());
    GetCurrentDirectoryW(MAX_PATH, directory);

    TCHAR fullName[MAX_PATH]; 

    StringCchCat(directory, MAX_PATH, L"\\");

    StringCchCopy(searchTemplate, MAX_PATH, directory); 
    StringCchCat(searchTemplate, MAX_PATH, L"*.txt");

    hFind = FindFirstFile(searchTemplate, &ffd);    

    if (GetLastError() == ERROR_FILE_NOT_FOUND) 
    {
        FindClose(hFind);
        return;
    }
    do
    {
        StringCchCopy(fullName, MAX_PATH, directory);
        StringCchCat(fullName, MAX_PATH, ffd.cFileName);

        folderCatalog.push_back(fullName);  
        fileNames.push_back(ffd.cFileName); 
    }
    while (FindNextFile(hFind, &ffd) != 0);

    FindClose(hFind);
    succeeded = true;
}

这是我需要将 System::String^ 转换为 TCHAR* 的地方

private: System::Void dienuFolderisToolStripMenuItem_Click(System::Object^
    sender, System::EventArgs^  e)
{
    FolderBrowserDialog^ dialog;
    dialog = gcnew System::Windows::Forms::FolderBrowserDialog;

    System::Windows::Forms::DialogResult result = dialog->ShowDialog();
    if (result == System::Windows::Forms::DialogResult::OK)
    {   
                     // Conversion is now working.          
         tstring path = marshal_as<tstring>(dialog->SelectedPath);
         folder->setDirectory(path);
    }
}

Answer 1

marsha_as "对特定数据对象执行封送处理以将其在托管数据类型和本机数据类型之间转换"。 Here 有可能的类型转换表。

我是这样用的：

marshal_as<std::wstring>(value)

TCHAR 可以是 char 或 wchar_t，它们都存在于 marshal_as 特化中，我想你需要将 TCHAR* 作为模板参数：

TCHAR* result = marshal_as<TCHAR*>(value)

其实MSDN说得这样用：

#include <msclr\marshal.h>

using namespace System;
using namespace msclr::interop;

int main(array<System::String ^> ^args)
{
    System::String^ managedString = gcnew System::String("Hello World!!!");

    marshal_context ^ context = gcnew marshal_context();
    const wchar_t* nativeString = context->marshal_as<const wchar_t*>(managedString);
    //use nativeString
    delete context;

    return 0;
}