How do I avoid ODR violations in shared libraries?

To avoid One Definition Rule (ODR) violations in shared libraries, it's essential to follow best practices in C++ programming. ODR violations occur when different translation units define the same entity in incompatible ways. Here are some strategies to help mitigate these issues:

Best Practices

• Use header guards or `#pragma once` to prevent multiple inclusions of the same header file.
• Prefer inline functions or templates for functionality that may be included in multiple translation units.
• Define global variables as `static` or use anonymous namespaces to limit their visibility.
• Ensure that you consistently use the same definition across all translation units.
• Utilize extern "C" for C++ code interfacing with C to avoid name mangling issues.

Example

#include <iostream>

    // Header guard to prevent ODR violation
    #ifndef MYLIB_H
    #define MYLIB_H

    // Function declaration
    void myFunction();

    #endif

    // Function definition
    void myFunction() {
        std::cout << "Hello, World!" << std::endl;
    }