Question

I am learning C and I am wondering what I need to add for those values in my WriteFile and ReadFile methods

lpNumberOfBytesRead and lpNumberOfBytesWritten

WriteFile((HANDLE)sock, "\x05\x01\x00", 3, NULL, NULL);
ReadFile((HANDLE)sock, buf, 1024, NULL, NULL);

it says in the documentation one of the two NULL values can’t be NULL as my friend pointed out…

Any ideas *cheers

Answer 1

Assuming that you are not going to use overlapped I/O, (and from your question, I get a strong feeling that you are not), you need to pass a pointer to a DWORD variable that will receive the values:

DWORD NumberOfBytesWritten;
WriteFile((HANDLE)sock, "\x05\x01\x00", 3, &NumberOfBytesWritten, NULL);

If the function returns successfully (and you should check its return value to determine that), NumberOfBytesWritten will be set to the number of bytes that were actually written to the file.