C++\CLI Windows Forms - creating external class - forms

Question

While making a simple windows forms application with VC++ I have a listview containing some files and their info. What I want to do is only show the filename in the list while storing the full filepath. I created an external class to do this:
class FileInfoContainer {
vector<string> filenames;
vector<int> uncompsize;
vector<int> compsize;
int getFileSize(string filepath);
public:
FileInfoContainer() {};
void AddItem(string filepath);
void AddItem(string filepath, int uncompsize, int compsize);
void AddItem(string filepath, int uncompsize);
string getItemFilename(int index);
int getItemCompsize(int index);
int getItemUncompsize(int index);
};
Now back to the automatic code generated by the VS template for this application, I tried to declare an instance of this class so that I can have the file information available anywhere within:
public ref class MainForm : public System::Windows::Forms::Form
{
public:
MainForm(void)
{
InitializeComponent();
}
protected:
~MainForm()
{
if (components)
{
delete components;
}
}
System::Windows::Forms::ListViewItem^ files; //my addition
FileInfoContainer compfiles; //my addition
private: System::Windows::Forms::OpenFileDialog^ openFileDialog1;
private: System::Windows::Forms::SaveFileDialog^ saveFileDialog1;
...........
}
This is generated code where I've only added those 2 lines, of which the first works normally while the second gives a member of managed class can't be non-managed class type error.
What can I do to go around this issue?