Debugging and Logging Techniques for MQL5 Trading Programs
Summary
The article compares three ways to find problems in Expert Advisors, scripts, and indicators: inspecting outputs, stepping through code with a debugger, and recording program events in logs. A small array-loop example shows how output and variable inspection can reveal an off-by-one error. The author describes logging as useful for both locating logic faults and monitoring running programs, including trade actions and optimization runs.
It reviews on-chart comments, alerts, printed messages, and file-based logging, outlining tradeoffs such as visibility, notification, performance, log separation, and ease of later review. File logging is presented as flexible because programs can write selected messages to separate files. The article then introduces a logger class and LogMon, a Windows utility for organizing, viewing, searching, and monitoring categorized log messages with notifications. These are practical development and operations aids, not trading signals; frequent logging can add runtime overhead, and the discussion reflects the platform and tools described in the article.
Key ideas
- Output inspection is quick but usually does not pinpoint where a program error occurs.
- Step-by-step debugging exposes runtime state but can be slow and unsuitable for monitoring a finished EA.
- Logs can record events during live execution and support later comparison, with some added runtime cost.
- Comments, alerts, printed messages, and file output differ in visibility, flexibility, and performance.
- A categorized logger and log viewer can make program messages easier to filter and monitor.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.