Internal and External Linkage

Managing Global Variables

What are some best practices for managing global variables in large projects?

Abstract art representing computer programming

Global variables can be tricky to manage, especially in large projects. They provide easy access across different parts of a program but can lead to maintenance challenges and unintended side effects. Here are some best practices for managing global variables effectively:

Best Practices

Minimize Use: Only use global variables when absolutely necessary. Prefer local variables or member variables of classes.

Naming Conventions: Use clear and consistent naming conventions to differentiate global variables from local ones. Consider prefixing global variable names (e.g., g_ for global).

Encapsulation: Encapsulate global variables within namespaces or classes to avoid naming conflicts. For example:

namespace Config {
  extern int ScreenWidth;
  extern int ScreenHeight;
}

Read-Only Globals: Make global variables const if they don't need to be modified. For example:

const int MaxUsers{100};

Initialization: Ensure global variables are initialized before use. Prefer to initialize them in the same file they are defined. For example:

// config.cpp
int Config::ScreenWidth{1920};
int Config::ScreenHeight{1080};

Documentation: Document global variables clearly, explaining their purpose and usage.

Thread Safety: Consider thread safety if your global variables are accessed from multiple threads. Use synchronization mechanisms like mutexes where necessary.

The following example combines many of these techniques:

// config.h
#pragma once

namespace Config {
  extern int ScreenWidth;
  extern int ScreenHeight;
}
// config.cpp
#include "config.h"

namespace Config {
  int ScreenWidth{1920};
  int ScreenHeight{1080};
}
// main.cpp
#include <iostream>
#include "config.h"

int main() {
  std::cout << "Screen Width: "
    << Config::ScreenWidth << '\n';
  std::cout << "Screen Height: "
    << Config::ScreenHeight << '\n';
}
g++ config.cpp main.cpp -o myProgram
./myProgram
Screen Width: 1920
Screen Height: 1080

Avoiding Common Pitfalls

  • Unintended Modifications: Limit write access to global variables. If a global variable must be modified, encapsulate the modification logic within functions or methods.
  • Hidden Dependencies: Avoid hidden dependencies by making it clear where and how global variables are used.

By following these best practices, you can manage global variables effectively in large projects, reducing the risk of bugs and making your code more maintainable and understandable.

This Question is from the Lesson:

Internal and External Linkage

A deeper look at the C++ linker and how it interacts with our variables and functions. We also cover how we can change those interactions, using the extern and inline keywords

Answers to questions are automatically generated and may not have been reviewed.

This Question is from the Lesson:

Internal and External Linkage

A deeper look at the C++ linker and how it interacts with our variables and functions. We also cover how we can change those interactions, using the extern and inline keywords

A computer programmer
Part of the course:

Professional C++

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Free, unlimited access

This course includes:

  • 124 Lessons
  • 550+ Code Samples
  • 96% Positive Reviews
  • Regularly Updated
  • Help and FAQ
Free, Unlimited Access

Professional C++

Comprehensive course covering advanced concepts, and how to use them on large-scale projects.

Screenshot from Warhammer: Total War
Screenshot from Tomb Raider
Screenshot from Jedi: Fallen Order
Contact|Privacy Policy|Terms of Use
Copyright © 2024 - All Rights Reserved