MQL5 File Handling and a Basic CSV Reader for Trading Systems
Summary
This practical guide explains how MQL5 programs can read text files from the platform’s permitted file area, open files with suitable modes, read lines to the end, and split rows into fields. It describes storing parsed rows in memory and using a header-to-column index map so an Expert Advisor can retrieve values by column name or position. The proposed reader can support external parameters, symbol lists, and other simple inputs without hard-coding them into the trading program.
The article emphasizes checking file-open failures, validating requested indexes or columns, and accounting for empty lines and inconsistent line endings. Its parsing approach is deliberately basic: splitting on a delimiter does not handle quoted CSV fields or delimiters embedded inside quotes. The text offers implementation guidance rather than trading results, and suggests that more complex files may require extensions for encoding, quoting, or other formatting needs.
Key ideas
- MQL5 file access is restricted to designated platform directories unless an allowed alternative is used.
- Text mode and an end-of-file check support line-by-line reading of simple data files.
- Splitting each row by a chosen delimiter provides fields that can be stored and queried by index.
- A header map can translate column names into indexes for convenient lookup.
- Basic delimiter splitting does not correctly parse quoted fields or embedded delimiters.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.