如何从C++中的字符串获取文件扩展名

#include<iostream>
#include<string>
#include<algorithm>

std::string get_file_extension(const std::string& file_name) {
    std::string extension = "";
    size_t last_dot = file_name.find_last_of('.');
    if (last_dot != std::string::npos) {
        extension = file_name.substr(last_dot + 1);
    }
    return extension;
}

int main() {
    std::string file_name = "example.txt";
    std::string extension = get_file_extension(file_name);
    std::cout << "File extension: "<< extension<< std::endl;
    return 0;
}

#include<iostream>
#include<filesystem>

std::string get_file_extension(const std::string& file_name) {
    std::filesystem::path file_path(file_name);
    return file_path.extension().string();
}

int main() {
    std::string file_name = "example.txt";
    std::string extension = get_file_extension(file_name);
    std::cout << "File extension: "<< extension<< std::endl;
    return 0;
}