std::filesystem (C++17)

In a Nutshell

A platform-independent filesystem library: path concatenation and normalization, directory creation and traversal, file copying and deletion, permission and status queries — say goodbye to stat() and opendir().

Header

#include <filesystem>

Core API Quick Reference

Operation	Signature	Description
Path class	class path	Path construction, concatenation, and decomposition (cross-platform separator handling)
Path concatenation	path operator/(const path& lhs, const path& rhs)	p / "subdir" / "file.txt"
Current path	path current_path()	Gets/sets the working directory
Directory iteration	class directory_iterator	Iterates a single-level directory
Recursive iteration	class recursive_directory_iterator	Recursively iterates subdirectories
File status	bool exists(const path& p)	Checks whether a path exists
File size	uintmax_t file_size(const path& p)	Gets the file size in bytes
Create directory	bool create_directory(const path& p)	Creates a single directory
Create multi-level directories	bool create_directories(const path& p)	Recursively creates the entire path
Copy file	bool copy_file(const path& from, const path& to)	Copies a single file
Delete	bool remove(const path& p)	Deletes a file or an empty directory
Recursive delete	uintmax_t remove_all(const path& p)	Recursively deletes a directory and its contents
Rename	void rename(const path& old, const path& newp)	Renames or moves

Minimal Example

// Standard: C++17
#include <filesystem>
#include <iostream>

namespace fs = std::filesystem;

int main() {
    fs::path p = fs::current_path() / "test.txt";
    std::cout << p << "\n";                      // full path
    std::cout << p.filename() << "\n";           // test.txt
    std::cout << p.extension() << "\n";          // .txt

    fs::create_directories("a/b/c");             // recursive creation
    std::cout << fs::exists("a/b") << "\n";      // true
    fs::remove_all("a");                         // recursive deletion
}

Embedded Applicability: Low

• Depends on the operating system's filesystem abstraction layer (POSIX or Win32); bare-metal environments have no filesystem
• Suitable for embedded Linux (e.g., Buildroot/Yocto platforms) or host-side configuration/logging tools
• The header carries considerable inclusion overhead; not recommended for extremely resource-constrained devices
• For embedded scenarios that do need a filesystem (e.g., FAT32 on an SD card), consider a lightweight alternative such as LittleFS

Compiler Support

GCC	Clang	MSVC
8	7	19.12

See Also

• Tutorial: std::filesystem
• cppreference: std::filesystem

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