I want to find log files ending with “access” and a number, such as 500m-access0.log.
My code :

bool is_access_log(const char *file_name)
{
    std::string name(file_name);
    struct stat file_info;
    if (stat(file_name, &file_info) < 0 || S_ISDIR((&file_info)->st_mode))
    {
        // return false if dir
        return false;
    }
    std::regex reg("(.)(-access)(\d).log");
    return std::regex_match(file_name, reg);
}

but I got false when I use 500m-access0.log and any_name-access3.log