Присвоение значения элементу структуры

struct Library
{
    int ID;
    double UDK;
    char Autor[50];
    char NameBook[100];
    int YearBook;
    int NumBook;
};
Library *M = new Library[50];

M[i].ID = i;
M[i].UDK = Convert::ToDouble(UDKBook->Text);
M[i].NameBook = Convert::ToChar(NameBook->Text);
M[i].Autor = Convert::ToChar(AutorBook->Text);
M[i].YearBook = Convert::ToInt16(YearBook->Text);
M[i].NumBook = Convert::ToInt16(NumberBook->Text);

#include <string>
using namespace System::Runtime::InteropServices;
...
System::String^ wstr = L"sometext";
const size_t buffSize = 100;
char buff[buffSize];
char* pbuff = buff;
IntPtr strPtr = (IntPtr)Marshal::StringToHGlobalAnsi(wstr);
strncpy_s(pbuff, buffSize, static_cast<const char*>(strPtr.ToPointer()), wstr->Length);
Marshal::FreeHGlobal(strPtr);