Mastering Data Management with the Demo_FileWriteArray EA in MetaTrader 5

If you're looking to enhance your trading strategy in MetaTrader 5, the Demo_FileWriteArray Expert Advisor (EA) is a game-changer. This EA captures the Bid and Ask prices with every tick and efficiently stores them in a structured array. Let’s dive into how it works and how you can leverage it for your trading.

How It Works

This EA operates by gathering Bid and Ask prices every tick and saving them into a "prices" structure array. Every twentieth tick, it writes this structured data into a binary file located in a subdirectory of your local terminal folder. To access the terminal's local folder, you can use the TerminalInfoString() function.

PrintFormat("The path to the terminal local folder: %s\\Files\\",TerminalInfoString(TERMINAL_DATA_PATH)); 

When you remove the EA from your chart, it ensures that any unsaved data is written to the file before terminating its operation.

Code Breakdown

Input Parameters:

//--- input parameters
input string InpFileName="data.bin";
input string InpDirectoryName="SomeFolder";

Structure for Storing Price Data:

//+------------------------------------------------------------------+
//| Structure for storing price data                                   |
//+------------------------------------------------------------------+
struct prices
  {
   datetime          date; // data
   double            bid;  // Bid price
   double            ask;  // Ask price
  };

Global Variables:

//--- global variables
int    count=0;
int    size=20;
string path=InpDirectoryName+"//"+InpFileName;
prices arr[];

Initialization and Deinitialization

The EA initializes by allocating memory for the array:

int OnInit()
  {
   //--- allocate memory for the array
   ArrayResize(arr,size);
   //---
   return(INIT_SUCCEEDED);
  }

When it’s time to remove the EA, it will write any remaining data:

void OnDeinit(const int reason)
  {
   //--- write the remaining count strings if count<n
   WriteData(count);
  }

Tick Function

With every tick, the EA saves the current data:

void OnTick()
  {
   //--- save data to array
   arr[count].date=TimeCurrent();
   arr[count].bid=SymbolInfoDouble(Symbol(),SYMBOL_BID);
   arr[count].ask=SymbolInfoDouble(Symbol(),SYMBOL_ASK);
   //--- show current data
   Print("Date = ",arr[count].date," Bid = ",arr[count].bid," Ask = ",arr[count].ask);
   //--- increase the counter
   count++;
   //--- if the array is filled, write data to the file and zero it out
   if(count==size)
     {
      WriteData(size);
      count=0;
     }
  }

Writing Data to File

Finally, the EA writes the collected data to a file:

void WriteData(const int n)
  {
   //--- open the file
   ResetLastError();
   int handle=FileOpen(path,FILE_READ|FILE_WRITE|FILE_BIN);
   if(handle!=INVALID_HANDLE)
     {
      //--- write array data to the end of the file
      FileSeek(handle,0,SEEK_END);
      FileWriteArray(handle,arr,0,n);
      //--- close the file
      FileClose(handle);
     }
   else
      Print("Failed to open the file, error ",GetLastError());
  }

Conclusion

The Demo_FileWriteArray EA is a powerful tool for traders looking to collect and manage their trading data effectively. By automating data capture and storage, you can focus on what really matters—making informed trading decisions. Give it a whirl and see how it can enhance your trading experience!