How to implement free pascal in Metatrader ?

Question

Kristy · Accepted Answer

To use Free Pascal with MetaTrader, you'll need to create a Dynamic Link Library (DLL) with your Free Pascal code and then integrate it into MetaTrader using MQL (MetaQuotes Language). This involves defining the functions you want to use in MQL and then compiling the DLL using Free Pascal and the appropriate settings. Here's a breakdown of the process:1. Free Pascal Development:Use an IDE like Lazarus or VS Code with the OmniPascal extension to write your Free Pascal code.Define functions that will be accessible from MQL. These functions should be declared with the external keyword.Ensure that the DLL is compiled with the correct settings to be loaded by MetaTrader.2. DLL Creation:Compile your Free Pascal project into a DLL (Dynamic Link Library).The DLL will contain the functions you defined in Free Pascal.3. MQL Integration:In your MQL5/4 expert advisor or indicator, you'll need to call the functions within the DLL.You'll use the LoadLibrary function to load the DLL.You can then use the GetProcAddress function to get the addresses of the functions within the DLL.Finally, you can call the functions using the retrieved addresses. Example of Free Pascal Code (creating a simple DLL): Codelibrary DLLTest;uses  System.SysUtils;{$mode objfpc}{$H+}function Add(a, b: integer): integer;  external 'Add' name 'Add';begin  Result := a + b;end;beginend.Example of MQL5 Integration (using the DLL): Code#property strict#property copyright "Your Name"#property link "Your Website"#import "DLLTest.dll" // Replace with your DLL filenameint Add(int a, int b);#endinputint OnInit(){    // Load the DLL    if (!LoadLibrary("DLLTest.dll"))    {        Print("Failed to load DLL");        return(INIT_FAILED);    }    // Perform operations using the DLL    int result = Add(5, 3);    Print("Result of DLL function: ", result);    return(INIT_SUCCEEDED);}void OnDeinit(){    // Unload the DLL    FreeLibrary("DLLTest.dll");}Key Considerations:Data Types:Ensure that data types in your Free Pascal code match those in your MQL code.Memory Management:Pay attention to memory allocation and deallocation when working with arrays or complex data structures in your Free Pascal code, especially if they are being passed to or from the DLL.Error Handling:Implement robust error handling in both your Free Pascal code and your MQL code to handle potential issues during DLL loading or function execution. By following these steps, you can effectively implement Free Pascal code within your MetaTrader platform by leveraging the power of DLLs and MQL.

Ginger · Answer

Implementing Free Pascal in MetaTrader involves creating Dynamic Link Libraries (DLLs) using Free Pascal and then calling functions from these DLLs within your MQL4/MQL5 code in MetaTrader.Steps to Implement Free Pascal in MetaTrader:Install Lazarus IDE with Free Pascal:Download and install Lazarus, which includes the Free Pascal compiler (FPC).Ensure you download the 32-bit version of Lazarus/FPC, even if you are on a 64-bit Windows, as MetaTrader is a 32-bit application and requires 32-bit DLLs.Create a New Library Project in Lazarus:Open Lazarus and go to Project -> New Project -> Library.Give your project a meaningful name and save it in an empty folder.This will create a .lpi file (compiler settings) and an .lpr file (source code).Write Your Pascal Code for the DLL:In the .lpr file, write the Pascal code for the functions you want to expose to MetaTrader.Use the exports keyword to make these functions accessible from the DLL.Example: Code        library MyMT4Lib;        uses          SysUtils;        function AddNumbers(a, b: Integer): Integer; stdcall;        begin          Result := a + b;        end;        exports          AddNumbers;        begin        end.The stdcall calling convention is crucial for compatibility with MetaTrader.Compile the Project to Create the DLL:Compile your Lazarus project. If configured correctly as a Library project, it will generate a .dll file in your project directory.Copy the DLL to MetaTrader's Experts/Libraries Folder:Locate the compiled .dll file.Copy this .dll file to the MQL4/Libraries (for MT4) or MQL5/Libraries (for MT5) folder within your MetaTrader data directory. You can find this by going to File -> Open Data Folder in MetaTrader.Declare and Call DLL Functions in MQL4/MQL5:In your MQL4/MQL5 Expert Advisor or Indicator, use the #import directive to declare the functions from your DLL.Example in MQL4/MQL5:C++        #import "MyMT4Lib.dll"        int AddNumbers(int a, int b);        #import        void OnStart()        {          int result = AddNumbers(5, 7);          Print("Result of AddNumbers: ", result);        }Enable DLL Imports in MetaTrader:In MetaTrader, go to Tools -> Options -> Expert Advisors and check the "Allow DLL imports" box.

How to implement free pascal in Metatrader ?

2 Answers

2 Answers

How to implement free pascal in Metatrader ?

2 Answers

2 Answers

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