File System Paths

Relative Paths Between Absolute Paths

How do I find the relative path between two absolute paths?

Abstract art representing computer programming

To find the relative path between two absolute paths in C++, you can use the std::filesystem::relative() function.

This function computes the relative path from one absolute path to another. Here’s how you can do it:

#include <filesystem>
#include <iostream>

int main() {
  std::filesystem::path base{
    R"(C:\Users\example\projects)"};
  std::filesystem::path target{
    R"(C:\Users\example\projects\subdir\file.txt)"};

  std::filesystem::path relativePath =
    std::filesystem::relative(target, base);
  std::cout << "Relative Path: "
    << relativePath.string();
}
Relative Path: subdir\file.txt

Key Points

  1. Base Path: The starting point from which you want to calculate the relative path.
  2. Target Path: The destination path you want to reach relative to the base path.
  3. Function: Use std::filesystem::relative(target, base) to compute the relative path.

Understanding Relative Paths

Relative paths are crucial when you want to specify paths relative to a certain directory, especially in projects that may be moved between different environments. This makes your code more flexible and portable.

Handling Different Platforms

std::filesystem::relative() handles platform-specific path separators, making it a robust solution for cross-platform applications. Whether you’re working on Windows with backslashes (\) or on Unix-like systems with forward slashes (/), the function ensures the correct path format.

Error Handling

Ensure both paths are absolute. If you pass relative paths to std::filesystem::relative(), it will throw an error. Here’s how to handle it:

#include <filesystem>
#include <iostream>

namespace fs = std::filesystem;

int main() {
  fs::path base{
    R"(C:\Users\example\projects)"};
  fs::path target{
    R"(C:\Users\example\projects\subdir\file.txt)"};

  try {
    fs::path relativePath =
      fs::relative(target, base);
    std::cout << "Relative Path: "
      << relativePath.string();
  } catch (const fs::filesystem_error& e) {
    std::cerr << "Error: " << e.what();
  }
}
Relative Path: subdir\file.txt

Conclusion

Finding the relative path between two absolute paths using std::filesystem::relative() is straightforward and ensures your paths remain flexible and portable. Always handle exceptions to manage any potential errors gracefully.

This Question is from the Lesson:

File System Paths

A guide to effectively working with file system paths, using the path type within the standard library's filesystem module.

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

This Question is from the Lesson:

File System Paths

A guide to effectively working with file system paths, using the path type within the standard library's filesystem module.

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