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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Mastering Log Records (Part 9): Implementing the builder pattern and adding default configurations

Mastering Log Records (Part 9): Implementing the builder pattern and adding default configurations

This article shows how to drastically simplify the use of the Logify library with the Builder pattern and automatic default configurations. It explains the structure of the specialized builders, how to use them with smart auto-completion, and how to ensure a functional log even without manual configuration. It also covers tweaks for MetaTrader 5 build 5100.
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MQL5 Wizard Techniques you should know (Part 30): Spotlight on Batch-Normalization in Machine Learning

MQL5 Wizard Techniques you should know (Part 30): Spotlight on Batch-Normalization in Machine Learning

Batch normalization is the pre-processing of data before it is fed into a machine learning algorithm, like a neural network. This is always done while being mindful of the type of Activation to be used by the algorithm. We therefore explore the different approaches that one can take in reaping the benefits of this, with the help of a wizard assembled Expert Advisor.
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Statistical Arbitrage Through Cointegrated Stocks (Part 4): Real-time Model Updating

Statistical Arbitrage Through Cointegrated Stocks (Part 4): Real-time Model Updating

This article describes a simple but comprehensive statistical arbitrage pipeline for trading a basket of cointegrated stocks. It includes a fully functional Python script for data download and storage; correlation, cointegration, and stationarity tests, along with a sample Metatrader 5 Service implementation for database updating, and the respective Expert Advisor. Some design choices are documented here for reference and for helping in the experiment replication.
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Mastering Log Records (Part 3): Exploring Handlers to Save Logs

Mastering Log Records (Part 3): Exploring Handlers to Save Logs

In this article, we will explore the concept of handlers in the logging library, understand how they work, and create three initial implementations: Console, Database, and File. We will cover everything from the basic structure of handlers to practical testing, preparing the ground for their full functionality in future articles.
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Mastering Log Records (Part 5): Optimizing the Handler with Cache and Rotation

Mastering Log Records (Part 5): Optimizing the Handler with Cache and Rotation

This article improves the logging library by adding formatters in handlers, the CIntervalWatcher class to manage execution cycles, optimization with caching and file rotation, performance tests and practical examples. With these improvements, we ensure an efficient, scalable and adaptable logging system to different development scenarios.
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From Basic to Intermediate: Definitions (II)

From Basic to Intermediate: Definitions (II)

In this article, we will continue our awareness of #define directive, but this time we will focus on its second form of use, that is, creating macros. Since this subject can be a bit complicated, we decided to use an application that we have been studying for some time. I hope you enjoy today's article.
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From Basic to Intermediate: Template and Typename (II)

From Basic to Intermediate: Template and Typename (II)

This article explains how to deal with one of the most difficult programming situations you can encounter: using different types in the same function or procedure template. Although we have spent most of our time focusing only on functions, everything covered here is useful and can be applied to procedures.
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Mastering Log Records (Part 8): Error Records That Translate Themselves

Mastering Log Records (Part 8): Error Records That Translate Themselves

In this eighth installment of the Mastering Log Records series, we explore the implementation of multilingual error messages in Logify, a powerful logging library for MQL5. You’ll learn how to structure errors with context, translate messages into multiple languages, and dynamically format logs by severity level. All of this with a clean, extensible, and production-ready design.
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Self Optimizing Expert Advisors in MQL5 (Part 14): Viewing Data Transformations as Tuning Parameters of Our Feedback Controller

Self Optimizing Expert Advisors in MQL5 (Part 14): Viewing Data Transformations as Tuning Parameters of Our Feedback Controller

Preprocessing is a powerful yet quickly overlooked tuning parameter. It lives in the shadows of its bigger brothers: optimizers and shiny model architectures. Small percentage improvements here can have disproportionately large, compounding effects on profitability and risk. Too often, this largely unexplored science is boiled down to a simple routine, seen only as a means to an end, when in reality it is where signal can be directly amplified, or just as easily destroyed.