dll questions

[Ming Luo]

Hi all:
I am quite confused about writing a indicator using C++ dll.

1. It seems that the DLL import must have a parameter, MT4 doesn't accept empty paramter function calls?

2. when I try to pass all the parameters in OnCalculate(...) to the dll function, it never works. Eventually, I split all the parameters into 3 functions and make it work. Is there a parameter number limitation in MT4 call dll???

int OnCalculate(const int rates_total, const int prev_calculated, const datetime &time[], const double &open[], const double &high[], const double &low[], const double &close[], const long &tick_volume[], const long &volume[], const int &spread[])

c++ dll............

YYH_SWING_API void SyncTime(int totalBars, int prev_Calculated, LONGLONG* time);
YYH_SWING_API void SyncPrice(double* open, double* high, double* low, double* close);
YYH_SWING_API void SyncVolume(LONGLONG* tickVolume, LONGLONG* volume, int* spread);


3. It there any better way to pass the data from MT4 to the DLL? Now it seems that I have to synchronize all the data and indicator every tick and it is very slow and inefficient.

Finally, is there any specification for MT4 calling DLL please???

Thanks