std::filesystem::path::extension

Since C++17

Returns the extension of the filename component of the generic-format view of *this.

# Declarations

path extension() const;

(since C++17)

# Return value

The extension of the current pathname or an empty path if there’s no extension.

# Notes

The extension as returned by this function includes a period to make it possible to distinguish the file that ends with a period (function returns “.”) from a file with no extension (function returns “”).

On a non-POSIX system, it is possible that p.stem() + p.extension() != p.filename() even though generic-format versions are the same.

# Example

#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;
 
int main()
{
    std::cout << fs::path("/foo/bar.txt").extension() << '\n'
              << fs::path("/foo/bar.").extension() << '\n'
              << fs::path("/foo/bar").extension() << '\n'
              << fs::path("/foo/bar.txt/bar.cc").extension() << '\n'
              << fs::path("/foo/bar.txt/bar.").extension() << '\n'
              << fs::path("/foo/bar.txt/bar").extension() << '\n'
              << fs::path("/foo/.").extension() << '\n'
              << fs::path("/foo/..").extension() << '\n'
              << fs::path("/foo/.hidden").extension() << '\n'
              << fs::path("/foo/..bar").extension() << '\n';
}

# See also