MT4: int init() → MT5: int OnInit()
This does not run the EX4 inside MT5, but it replicates the outcomes.
If you are using a commercial EA or a popular custom indicator found online, the best course of action is often the simplest: How To Use Ex4 File In Mt5
You cannot directly use EX4 files in MT5 .
Examples:
When purchasing any algorithm, always demand an MQL5 version or the source code with resale rights.
This is important because EX4 files are "closed source." You cannot open them to read the logic inside; you can only run them. This protects the intellectual property of the developer. MT4: int init() → MT5: int OnInit() This
Most are fake. A few advanced tools can decompile simple EX4 to MQ4, but the MQ4 → MQL5 conversion is still manual. For complex EAs, expect errors.
When you install MT5, it actually comes equipped with a tool designed specifically to help migrating users. This tool allows MT5 to run EX4 files, essentially acting as a compatibility layer. This is important because EX4 files are "closed source