using un-managed code in C#

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C++

C#

PInvoke

As in C # use the following code:
Cutting simple

Header.h

extern "C" class __declspec (dllexport)  MyClass
public:
{bool Open(int port, int baud);}

Prog.cpp

extern "C" __declspec (dllexport) bool MyClass::Open(int port, int baud)
{
    char COM_string[20];
    sprintf(COM_string,"\\\\.\\COM%d", port);

    m_hFile = CreateFile(COM_string, GENERIC_READ|GENERIC_WRITE, 0, NULL,
       OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,NULL);


    if(m_hFile == INVALID_HANDLE_VALUE)
    {
        return false;
    }
}

This is compiled into the library MyLybrary.dll
In C # I use the attribute:

[DllImport("MyLybrary", EntryPoint = "Open")]
            public static extern bool Open(int port, int baud);

But the call Open() to get the message: Can not find an entry point Open.

The problem is the use of Class MyClass?