Cookbooks
C++
Chapter 6. Files and I/O
Checking if a directory exists

C++:
Checking if a directory exists

How to:

In modern C++ (C++17 and beyond), you can use the filesystem library to check if a directory exists. It provides a straightforward and standardized way to perform filesystem operations, including checking for the existence of a directory.

#include <iostream>
#include <filesystem>

namespace fs = std::filesystem;

int main() {
    const fs::path dirPath = "/path/to/directory";

    if (fs::exists(dirPath) && fs::is_directory(dirPath)) {
        std::cout << "The directory exists." << std::endl;
    } else {
        std::cout << "The directory does not exist." << std::endl;
    }

    return 0;
}

Sample output if the directory exists:

The directory exists.

Sample output if the directory does not exist:

The directory does not exist.

For projects that are not yet using C++17 or for additional features, the Boost Filesystem library is a popular third-party choice that offers similar functionality.

#include <iostream>
#include <boost/filesystem.hpp>

namespace fs = boost::filesystem;

int main() {
    const fs::path dirPath = "/path/to/directory";

    if (fs::exists(dirPath) && fs::is_directory(dirPath)) {
        std::cout << "The directory exists." << std::endl;
    } else {
        std::cout << "The directory does not exist." << std::endl;
    }

    return 0;
}

Using Boost Filesystem, the output would be identical to the C++17 filesystem example, depending on the existence of the directory at the specified path.

Creating a temporary file