System::String ^ to LPCVOID conversion? [modified]

[Mattzimmerer]

Im trying to use WriteFile() to communicate with a driver, the information its sending is to be text from a Windows Forms textbox. I've tried so much to get it to work properly but it only seems to work if I do the following for WriteFile(): WriteFile(hFile, "this is the only way it works", sizeof("this is the only way it works");, &dwReturn, NULL); Im pretty lost and I would appreciate any help! Heres what my code looks like:

System::String ^str = this->Address->Text; //ANOTHER QUESTION.. WHATS THE ^ mean before str? Or where can I read about this operator?
LPCVOID lpBuffer = str;
/*BOOL WINAPI WriteFile(
__in HANDLE hFile,
__in LPCVOID lpBuffer,
__in DWORD nNumberOfBytesToWrite,
__out_opt LPDWORD lpNumberOfBytesWritten,
__inout_opt LPOVERLAPPED lpOverlapped );*/
WriteFile(hFile, lpBuffer, sizeof(lpBuffer), &dwReturn, NULL);
CloseHandle(hFile);

and the compiler output: 1>c:\users\matt_zimmerer_testos\desktop\zmdalpha1.0\gui\zmdinterface\Form1.h(170) : error C2440: 'initializing' : cannot convert from 'System::String ^' to 'LPCVOID' EDIT: minor grammar error fixed

modified on Saturday, January 2, 2010 5:06 PM

[Lost User]

System::String is a managed type and needs to be converted to a character array before you can cast it to a simple pointer. Take a look at the System::String[^] class, for more information.