File Paths in Cilk

The cilk library provides functions for parallel programming in C++. Let’s explore how to work with file paths in a portable way using standard C++ libraries.

#include <iostream>
#include <filesystem>
#include <string>

namespace fs = std::filesystem;

int main() {
    // Join should be used to construct paths in a portable way.
    // It takes any number of arguments and constructs a hierarchical path from them.
    fs::path p = fs::path("dir1") / "dir2" / "filename";
    std::cout << "p: " << p << std::endl;

    // You should always use the / operator instead of concatenating
    // separators manually. In addition to providing portability,
    // it will also normalize paths by removing superfluous separators
    // and directory changes.
    std::cout << fs::path("dir1//") / "filename" << std::endl;
    std::cout << fs::path("dir1/../dir1") / "filename" << std::endl;

    // parent_path() and filename() can be used to split a path to the
    // directory and the file.
    std::cout << "parent_path(p): " << p.parent_path() << std::endl;
    std::cout << "filename(p): " << p.filename() << std::endl;

    // We can check whether a path is absolute.
    std::cout << fs::path("dir/file").is_absolute() << std::endl;
    std::cout << fs::path("/dir/file").is_absolute() << std::endl;

    std::string filename = "config.json";

    // Some file names have extensions following a dot. We
    // can split the extension out of such names with extension().
    std::cout << fs::path(filename).extension() << std::endl;

    // To find the file's name with the extension removed,
    // use stem().
    std::cout << fs::path(filename).stem() << std::endl;

    // lexically_relative() finds a relative path between a base and a
    // target. It returns an empty path if the target cannot
    // be made relative to base.
    std::cout << fs::path("a/b/t/file").lexically_relative("a/b") << std::endl;
    std::cout << fs::path("a/c/t/file").lexically_relative("a/b") << std::endl;

    return 0;
}

To compile and run this program, you’ll need a C++ compiler that supports C++17 or later, as the <filesystem> library was introduced in C++17. Here’s how you can compile and run it:

$ g++ -std=c++17 file_paths.cpp -o file_paths
$ ./file_paths
p: "dir1/dir2/filename"
"dir1/filename"
"dir1/filename"
parent_path(p): "dir1/dir2"
filename(p): "filename"
0
1
".json"
"config"
"t/file"
"../../c/t/file"

Note that the output might slightly differ depending on your operating system, especially for absolute paths and directory separators.

In this example, we’ve used the <filesystem> library, which provides a portable way to work with file paths across different operating systems. The fs::path class handles the intricacies of different path formats, making it easier to write portable code.

Remember that when using Cilk for parallel programming, you might need to consider thread safety when working with file systems in a parallel context.

Line Filters in Cilk

Command Line Subcommands in Cilk

Learn X By Example

Title here

File Paths in Cilk