MetaTrader 5 MQL Integration Example

Example of how to call C++ / C# functions from MetaTrader 5 MQL Expert Advisors, Indicators, etc

SUPER IMPORTANT: Build both projects in x64 or MT5 won't see the exported functions !

CSharp

1. Create regular class library (dll) with Visual Studio/MonoDevelop/Xamarin
2. Include NuGet package UnmanagedExports
3. Attach DllExport attribute to every public static method you want to export

[DllExport("Add", CallingConvention = CallingConvention.StdCall)]
public static int Add(int left, int right)
{
    return left + right;
}

More examples (Section 4, working with arrays): https://www.mql5.com/en/articles/249

Visual C++

1. Create Win32 project and from the wizard change project type from Windows Application to DLL
2. Mark the functions you want to export:

extern "C" __declspec(dllexport) 
int __stdcall MyFunc() { 
	return 42;
}

More examples (working with arrays): https://www.mql5.com/en/articles/18

MQL5

• Copy your DLL files to <terminal_path>/MQL5/Libraries. You can also change output of your project to that path
• Import DLL files and describe functions

// VC++
#import "MQLIntegrationVCpp.dll"
   int GetTheAnswerOfEverything();
#import

// C#
#import "MQLIntegrationCs.dll"
   int Add(int left,int right);
   int Sub(int left,int right);
   float AddFloat(float left,float right);
   double AddDouble(double left,double right);
#import

int OnInit()
{  
  Print("############ Gateway initiated");
 
  Print("Hello C#: 2+3 = ",Add(2, 3)); // 5
  Print("Hello VC++: The answer is ", GetTheAnswerOfEverything()); // 42

  return(INIT_SUCCEEDED);
}