统计文件目录下所有文件个数并打印文件名

/*  利用boost库中的filesystem可以轻松的实现计算某一目录下的文件个数及名字（包括子目录）
本程序采用了命令行参数的形式
结果存储在另一txt文件中
*/
#include <boost/filesystem.hpp>
#include <iostream>
#include <string>
#include <fstream>
#include <vector>
#include <boost/program_options.hpp>

namespace fs = boost::filesystem;
namespace po = boost::program_options;

int get_filenames(const std::string& dir, std::vector<std::string>& filenames)   //获取文件名和个数
{
fs::path path(dir);
if (!fs::exists(path))  //判断文件路径是否为空
{
return -1;
}

fs::directory_iterator end_iter;
for (fs::directory_iterator iter(path); iter!=end_iter; ++iter)
{
if (fs::is_regular_file(iter->status()))
{
filenames.push_back(iter->path().string());
}

if (fs::is_directory(iter->status()))
{
get_filenames(iter->path().string(), filenames);//是目录则递归
}
}

return filenames.size();  //返回文件大小
}

int main(int argc,char *argv[])
{
po::options_description desc("Allowed options");
desc.add_options()
("help,h", "produce help message")
("directory,d",po::value<std::string>(), "output files' name and amount");

po::variables_map vm;
po::store(po::parse_command_line(argc, argv, desc), vm);
po::notify(vm);

if(vm.count("help"))
{
std::cout<<desc<<std::endl;
return 1;
}

if(vm.count("directory"))
{
std::vector<std::string> filenames;
int amount = get_filenames(vm["directory"].as<std::string>(),filenames);
std::ofstream out("filenames.txt");
if (out.fail())
{
std::cout << "Error 2: failed to open the destination file." << std::endl;
out.close();
return 0;
}
if (out.is_open())
{
out <<"amount:"<<amount<<"  \n";
for(std::vector<std::string>::iterator iter = filenames.begin(); iter != filenames.end(); iter++ )
{
out<<*iter<<" \n";
}
out.close();
}
}
else
{
std::cout<<"error1"<<std::endl;
}
return 0;
}