MQL4 and MQL5 Programming Articles

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Study the MQL5 language for programming trading strategies in numerous published articles mostly written by you - the community members. The articles are grouped into categories to help you quicker find answers to any questions related to programming: Integration, Tester, Trading Strategies, etc.

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From Basic to Intermediate: Template and Typename (III)

From Basic to Intermediate: Template and Typename (III)

In this article, we will discuss the first part of the topic, which is not so easy for beginners to understand. In order not to get even more confused and to explain this topic correctly, we will divide the explanation into stages. We will devote this article to the first stage. However, although at the end of the article it may seem that we have reached the deadlock, in fact we will take a step towards another situation, which will be better understood in the next article.
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Engineering Trading Discipline into Code (Part 5): Account-Level Risk Enforcement in MQL5

Engineering Trading Discipline into Code (Part 5): Account-Level Risk Enforcement in MQL5

We introduce an MQL5 discipline engine that enforces risk consistently at the account level. It continuously scans positions from any source, validates SL/TP, equity-based exposure, and target R:R, and automatically corrects deviations by setting levels or adjusting volume. The result is uniform risk structure across manual and EA trades, supported by on-chart feedback and mode-based control.
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Account Audit System in MQL5 (Part 1): Designing the User Interface

Account Audit System in MQL5 (Part 1): Designing the User Interface

This article builds the user interface layer of an Account Audit System in MQL5 using CChartObject classes. We construct an on-chart dashboard that displays key metrics such as start/end balance, net profit, total trades, wins/losses, win rate, withdrawals, and a star-based performance rating. A menu button lets you show or hide the panel and restores one-click trading, delivering a clean, usable foundation for the broader audit pipeline.
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Neural networks are easy (Part 59): Dichotomy of Control (DoC)

Neural networks are easy (Part 59): Dichotomy of Control (DoC)

In the previous article, we got acquainted with the Decision Transformer. But the complex stochastic environment of the foreign exchange market did not allow us to fully implement the potential of the presented method. In this article, I will introduce an algorithm that is aimed at improving the performance of algorithms in stochastic environments.
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Neural Network in Practice: Least Squares

Neural Network in Practice: Least Squares

In this article, we'll look at a few ideas, including how mathematical formulas are more complex in appearance than when implemented in code. In addition, we will consider how to set up a chart quadrant, as well as one interesting problem that may arise in your MQL5 code. Although, to be honest, I still don't quite understand how to explain it. Anyway, I'll show you how to fix it in code.
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MQL5 Wizard Techniques you should know (Part 52): Accelerator Oscillator

MQL5 Wizard Techniques you should know (Part 52): Accelerator Oscillator

The Accelerator Oscillator is another Bill Williams Indicator that tracks price momentum's acceleration and not just its pace. Although much like the Awesome oscillator we reviewed in a recent article, it seeks to avoid the lagging effects by focusing more on acceleration as opposed to just speed. We examine as always what patterns we can get from this and also what significance each could have in trading via a wizard assembled Expert Advisor.
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Category Theory in MQL5 (Part 17): Functors and Monoids

Category Theory in MQL5 (Part 17): Functors and Monoids

This article, the final in our series to tackle functors as a subject, revisits monoids as a category. Monoids which we have already introduced in these series are used here to aid in position sizing, together with multi-layer perceptrons.
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Feature Engineering for ML (Part 1): Fractional Differentiation — Stationarity Without Memory Loss

Feature Engineering for ML (Part 1): Fractional Differentiation — Stationarity Without Memory Loss

Integer differentiation forces a binary choice between stationarity and memory: returns (d=1) are stationary but discard all price-level information; raw prices (d=0) preserve memory but violate ML stationarity assumptions. We implement the fixed-width fractional differentiation (FFD) method from AFML Chapter 5, covering get_weights_ffd (iterative recurrence with threshold cutoff), frac_diff_ffd (bounded dot product per bar), and fracdiff_optimal (binary search for minimum stationary d*).
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Most notable Artificial Cooperative Search algorithm modifications (ACSm)

Most notable Artificial Cooperative Search algorithm modifications (ACSm)

Here we will consider the evolution of the ACS algorithm: three modifications aimed at improving the convergence characteristics and the algorithm efficiency. Transformation of one of the leading optimization algorithms. From matrix modifications to revolutionary approaches regarding population formation.
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Self Optimizing Expert Advisor With MQL5 And Python (Part VI): Taking Advantage of Deep Double Descent

Self Optimizing Expert Advisor With MQL5 And Python (Part VI): Taking Advantage of Deep Double Descent

Traditional machine learning teaches practitioners to be vigilant not to overfit their models. However, this ideology is being challenged by new insights published by diligent researches from Harvard, who have discovered that what appears to be overfitting may in some circumstances be the results of terminating your training procedures prematurely. We will demonstrate how we can use the ideas published in the research paper, to improve our use of AI in forecasting market returns.
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Neural networks made easy (Part 82): Ordinary Differential Equation models (NeuralODE)

Neural networks made easy (Part 82): Ordinary Differential Equation models (NeuralODE)

In this article, we will discuss another type of models that are aimed at studying the dynamics of the environmental state.
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Overcoming The Limitation of Machine Learning (Part 7): Automatic Strategy Selection

Overcoming The Limitation of Machine Learning (Part 7): Automatic Strategy Selection

This article demonstrates how to automatically identify potentially profitable trading strategies using MetaTrader 5. White-box solutions, powered by unsupervised matrix factorization, are faster to configure, more interpretable, and provide clear guidance on which strategies to retain. Black-box solutions, while more time-consuming, are better suited for complex market conditions that white-box approaches may not capture. Join us as we discuss how our trading strategies can help us carefully identify profitable strategies under any circumstance.
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From CPU to GPU in MQL5: A Practical OpenCL Framework for Accelerating Research, Optimizations, and Patterns

From CPU to GPU in MQL5: A Practical OpenCL Framework for Accelerating Research, Optimizations, and Patterns

Find out how to build a practical CPU-to-GPU migration path in MQL5 using OpenCL. We will focus on context initialization, buffer organization, large batches, kernel startup, and minimizing data exchanges. Typical errors and ways to eliminate them will be considered as well. An example with candlestick patterns illustrates the practical benefit of the approach.
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Data Science and ML (Part 44): Forex OHLC Time series Forecasting using Vector Autoregression (VAR)

Data Science and ML (Part 44): Forex OHLC Time series Forecasting using Vector Autoregression (VAR)

Explore how Vector Autoregression (VAR) models can forecast Forex OHLC (Open, High, Low, and Close) time series data. This article covers VAR implementation, model training, and real-time forecasting in MetaTrader 5, helping traders analyze interdependent currency movements and improve their trading strategies.
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Developing a Multi-Currency Advisor (Part 27): Component for Displaying Multi-Line Text

Developing a Multi-Currency Advisor (Part 27): Component for Displaying Multi-Line Text

If there is a need to display text on a chart, we can use the Comment() function. But its capabilities are quite limited. Therefore, in this article, we will create our own component - a full-screen dialog window capable of displaying multi-line text with flexible font settings and scrolling support.
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Chemical reaction optimization (CRO) algorithm (Part I): Process chemistry in optimization

Chemical reaction optimization (CRO) algorithm (Part I): Process chemistry in optimization

In the first part of this article, we will dive into the world of chemical reactions and discover a new approach to optimization! Chemical reaction optimization (CRO) uses principles derived from the laws of thermodynamics to achieve efficient results. We will reveal the secrets of decomposition, synthesis and other chemical processes that became the basis of this innovative method.
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Developing a Replay System (Part 69): Getting the Time Right (II)

Developing a Replay System (Part 69): Getting the Time Right (II)

Today we will look at why we need the iSpread feature. At the same time, we will understand how the system informs us about the remaining time of the bar when there is not a single tick available for it. The content presented here is intended solely for educational purposes. Under no circumstances should the application be viewed for any purpose other than to learn and master the concepts presented.
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The MQL5 Standard Library Explorer (Part 2): Connecting Library Components

The MQL5 Standard Library Explorer (Part 2): Connecting Library Components

Today, we take an important step toward helping every developer understand how to read class structures and quickly build Expert Advisors using the MQL5 Standard Library. The library is rich and expandable, yet it can feel like being handed a complex toolkit without a manual. Here we share and discuss an alternative integration routine—a concise, repeatable workflow that shows how to connect classes reliably in real projects.
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Developing a Replay System (Part 33): Order System (II)

Developing a Replay System (Part 33): Order System (II)

Today we will continue to develop the order system. As you will see, we will be massively reusing what has already been shown in other articles. Nevertheless, you will receive a small reward in this article. First, we will develop a system that can be used with a real trading server, both from a demo account or from a real one. We will make extensive use of the MetaTrader 5 platform, which will provide us with all the necessary support from the beginning.
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Overcoming The Limitation of Machine Learning (Part 2): Lack of Reproducibility

Overcoming The Limitation of Machine Learning (Part 2): Lack of Reproducibility

The article explores why trading results can differ significantly between brokers, even when using the same strategy and financial symbol, due to decentralized pricing and data discrepancies. The piece helps MQL5 developers understand why their products may receive mixed reviews on the MQL5 Marketplace, and urges developers to tailor their approaches to specific brokers to ensure transparent and reproducible outcomes. This could grow to become an important domain-bound best practice that will serve our community well if the practice were to be widely adopted.
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Developing an MQTT client for MetaTrader 5: a TDD approach — Part 2

Developing an MQTT client for MetaTrader 5: a TDD approach — Part 2

This article is part of a series describing our development steps of a native MQL5 client for the MQTT protocol. In this part we describe our code organization, the first header files and classes, and how we are writing our tests. This article also includes brief notes about the Test-Driven-Development practice and how we are applying it to this project.
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Market Simulation (Part 21): First Steps with SQL (IV)

Market Simulation (Part 21): First Steps with SQL (IV)

Many of you may have far more experience working with databases than I do, and therefore may have a different opinion. Since it was necessary to explain why databases are designed the way they are, and why SQL has the form it does—especially why primary and foreign keys emerged—some things had to remain somewhat abstract.
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Neural Networks in Trading: Hierarchical Dual-Tower Transformer (Final Part)

Neural Networks in Trading: Hierarchical Dual-Tower Transformer (Final Part)

We continue to build the Hidformer hierarchical dual-tower transformer model designed for analyzing and forecasting complex multivariate time series. In this article, we will bring the work we started earlier to its logical conclusion — we will test the model on real historical data.
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Population optimization algorithms: Whale Optimization Algorithm (WOA)

Population optimization algorithms: Whale Optimization Algorithm (WOA)

Whale Optimization Algorithm (WOA) is a metaheuristic algorithm inspired by the behavior and hunting strategies of humpback whales. The main idea of WOA is to mimic the so-called "bubble-net" feeding method, in which whales create bubbles around prey and then attack it in a spiral motion.
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3D Visualization Without External Libraries: How MetaTrader 5 Reveals Optimization Results via MQL5 + DX11

3D Visualization Without External Libraries: How MetaTrader 5 Reveals Optimization Results via MQL5 + DX11

The article describes the practical application of DirectX 11 and built-in MQL5 tools for creating 3D visualizations and interactive interfaces in MetaTrader 5. The focus is on cognitive efficiency - the ability of 3D charts and guided scenes to help in understanding optimization data, liquidity clusters, and multi-dimensional trading scenarios. The basics of the DX pipeline, working with shaders, binding mouse and keyboard events, and objective technological limitations are discussed in detail. The article is intended for MQL5 developers and algorithmic traders who are ready to transform strategy metrics into understandable 3D analytical landscapes, where the visual layer accelerates decision-making.
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Market Simulation (Part 10): Sockets (IV)

Market Simulation (Part 10): Sockets (IV)

In this article, we'll look at what you need to do to start using Excel to manage MetaTrader 5, but in a very interesting way. To do this, we will use an Excel add-in to avoid using built-in VBA. If you don't know what add-in is meant, read this article and learn how to program in Python directly in Excel.
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African Buffalo Optimization (ABO)

African Buffalo Optimization (ABO)

The article presents the African Buffalo Optimization (ABO) algorithm, a metaheuristic approach developed in 2015 based on the unique behavior of these animals. The article describes in detail the stages of the algorithm implementation and its efficiency in finding solutions to complex problems, which makes it a valuable tool in the field of optimization.
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MQL5 Wizard Techniques You Should Know (Part 15): Support Vector Machines with Newton's Polynomial

MQL5 Wizard Techniques You Should Know (Part 15): Support Vector Machines with Newton's Polynomial

Support Vector Machines classify data based on predefined classes by exploring the effects of increasing its dimensionality. It is a supervised learning method that is fairly complex given its potential to deal with multi-dimensioned data. For this article we consider how it’s very basic implementation of 2-dimensioned data can be done more efficiently with Newton’s Polynomial when classifying price-action.
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Using the MQL5 Economic Calendar for News Filter (Part 3): Surviving Terminal Restarts During News Window

Using the MQL5 Economic Calendar for News Filter (Part 3): Surviving Terminal Restarts During News Window

The article introduces a restart-safe storage model for news-time stop removal. Suspension state and original SL/TP per position are written to terminal global variables, reconstructed on OnInit, and cleaned after restoration. This lets the EA resume an active suspension window after recompiles or restarts and restore stops only when the news window ends.
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Battle Royale Optimizer (BRO)

Battle Royale Optimizer (BRO)

The article explores the Battle Royale Optimizer algorithm — a metaheuristic in which solutions compete with their nearest neighbors, accumulate “damage,” are replaced when a threshold is exceeded, and periodically shrink the search space around the current best solution. It presents both pseudocode and an MQL5 implementation of the CAOBRO class, including neighbor search, movement toward the best solution, and an adaptive delta interval. Test results on the Hilly, Forest, and Megacity functions highlight the strengths and limitations of the approach. The reader is provided with a ready-to-use foundation for experimentation and tuning key parameters such as popSize and maxDamage.
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Generative Adversarial Networks (GANs) for Synthetic Data in Financial Modeling (Part 2): Creating Synthetic Symbol for Testing

Generative Adversarial Networks (GANs) for Synthetic Data in Financial Modeling (Part 2): Creating Synthetic Symbol for Testing

In this article we are creating a synthetic symbol using a Generative Adversarial Network (GAN) involves generating realistic Financial data that mimics the behavior of actual market instruments, such as EURUSD. The GAN model learns patterns and volatility from historical market data and creates synthetic price data with similar characteristics.
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Ordinal Encoding for Nominal Variables

Ordinal Encoding for Nominal Variables

In this article, we discuss and demonstrate how to convert nominal predictors into numerical formats that are suitable for machine learning algorithms, using both Python and MQL5.
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Category Theory in MQL5 (Part 12): Orders

Category Theory in MQL5 (Part 12): Orders

This article which is part of a series that follows Category Theory implementation of Graphs in MQL5, delves in Orders. We examine how concepts of Order-Theory can support monoid sets in informing trade decisions by considering two major ordering types.
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Market Simulation (Part 02): Cross Orders (II)

Market Simulation (Part 02): Cross Orders (II)

Unlike what was done in the previous article, here we will test the selection option using an Expert Advisor. Although this is not a final solution yet, it will be enough for now. With the help of this article, you will be able to understand how to implement one of the possible solutions.
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Hybridization of population algorithms. Sequential and parallel structures

Hybridization of population algorithms. Sequential and parallel structures

Here we will dive into the world of hybridization of optimization algorithms by looking at three key types: strategy mixing, sequential and parallel hybridization. We will conduct a series of experiments combining and testing relevant optimization algorithms.
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Brain Storm Optimization algorithm (Part I): Clustering

Brain Storm Optimization algorithm (Part I): Clustering

In this article, we will look at an innovative optimization method called BSO (Brain Storm Optimization) inspired by a natural phenomenon called "brainstorming". We will also discuss a new approach to solving multimodal optimization problems the BSO method applies. It allows finding multiple optimal solutions without the need to pre-determine the number of subpopulations. We will also consider the K-Means and K-Means++ clustering methods.
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Building Volatility models in MQL5 (Part I): The Initial Implementation

Building Volatility models in MQL5 (Part I): The Initial Implementation

In this article, we present an MQL5 library for modeling volatility, designed to function similarly to Python's arch package. The library currently supports the specification of common conditional mean (HAR, AR, Constant Mean, Zero Mean) and conditional volatility (Constant Variance, ARCH, GARCH) models.
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Mutual information as criteria for Stepwise Feature Selection

Mutual information as criteria for Stepwise Feature Selection

In this article, we present an MQL5 implementation of Stepwise Feature Selection based on the mutual information between an optimal predictor set and a target variable.
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Market Simulation (Part 19): First Steps with SQL (II)

Market Simulation (Part 19): First Steps with SQL (II)

As we explained in the first article about SQL, there is no point in spending time programming procedures to do what is already built into SQL. However, without knowing the basics, you won’t be able to do anything with SQL or take full advantage of everything this tool offers. Therefore, in this article, we will look at how to perform basic tasks in databases.
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Statistical Arbitrage Through Cointegrated Stocks (Part 9): Backtesting Portfolio Weights Updates

Statistical Arbitrage Through Cointegrated Stocks (Part 9): Backtesting Portfolio Weights Updates

This article describes the use of CSV files for backtesting portfolio weights updates in a mean-reversion-based strategy that uses statistical arbitrage through cointegrated stocks. It goes from feeding the database with the results of a Rolling Windows Eigenvector Comparison (RWEC) to comparing the backtest reports. In the meantime, the article details the role of each RWEC parameter and its impact in the overall backtest result, showing how the comparison of the relative drawdown can help us to further improve those parameters.