Using External Libraries and Files in MQL4

External libraries and files can significantly enhance the functionalities of MQL4 programs. They allow developers to reuse code, leverage additional capabilities, and access external data. Here's how to use them:

1. MQL4 Libraries (.mqh files)

Libraries in MQL4 are stored in .mqh files and usually contain functions and procedures that can be used across different MQL4 programs.

2. External DLL Libraries

MQL4 allows importing functions from DLLs. This capability significantly broadens what you can do with MQL4, as it enables you to use functions not natively available in MQL4.

3. Reading and Writing Files

MQL4 provides functions to read from and write to external files, enabling strategies that rely on external data or saving data for external analysis.

4. Security Concerns

While external libraries and files enhance functionality, they also pose potential security risks, especially when using third-party DLLs. Always ensure the source's trustworthiness and be wary of potential malicious code.


By leveraging external libraries and files, MQL4 developers can create more versatile, data-rich, and efficient programs. However, always prioritize security, especially when integrating external components.

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