遍历读取指定文件夹下指定类型的所有文件

经常碰到朋友，尤其是初学者对指定文件夹下指定类型文件的读取很困惑，这里，我把自己经常用的程序贴出来，供初学者学些；

#include "stdafx.h"
#include "windows.h"
#include <vector>
#include <string>
#include "iostream"
using namespace std;
typedef std::vector<std::string> file_lists;

static int str_compare(const void *arg1, const void *arg2)
{
       return strcmp((*(std::string*)arg1).c_str(), (*(std::string*)arg2).c_str());//比较字符串arg1 and arg2
}

file_lists ScanDirectory(const std::string &path, const std::string &extension)
{
    WIN32_FIND_DATA wfd;//WIN32_FIND_DATA:Contains information about the file that is found by the 
        //FindFirstFile, FindFirstFileEx, or FindNextFile function
     HANDLE hHandle;
     string searchPath, searchFile;
     file_lists vFilenames;
     int nbFiles = 0;
    
     searchPath = path + "/*" + extension;
     hHandle = FindFirstFile(searchPath.c_str(), &wfd);//Searches a directory for a file or subdirectory
              //with a name that matches a specific name
     if (INVALID_HANDLE_VALUE == hHandle)
    {
         fprintf(stderr, "ERROR(%s, %d): Cannot find (*.%s)files in directory %s/n",
              __FILE__, __LINE__, extension.c_str(), path.c_str());
         exit(0);
    }
    do
    {
         //. or ..
          if (wfd.cFileName[0] == '.')
         {
              continue;
          }
          // if exists sub-directory
          if (wfd.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)//dwFileAttributes:The file attributes of a file
        {             

          //FILE_ATTRIBUTE_DIRECTORY:The handle identifies a directory
             continue;
         }
        else//if file
        {
            searchFile = path + "/" + wfd.cFileName;
            vFilenames.push_back(searchFile);
            nbFiles++;
         }
    }while (FindNextFile(hHandle, &wfd));//Call this member function to continue a file search begun 
          //with a call to CGopherFileFind::FindFile

    FindClose(hHandle);//Closes a file search handle opened by the FindFirstFile, FindFirstFileEx,
       //or FindFirstStreamW function

 // sort the filenames
    qsort((void *)&(vFilenames[0]), (size_t)nbFiles, sizeof(string), str_compare);//Performs a quick sort

    return vFilenames;
}

int _tmain(int argc, _TCHAR* argv[])
{
     file_lists files = ScanDirectory("D://PicturesForTestInTheHall//TestGroup5", ".jpg");
     if (files.empty())
     {
          cout<<"no image file find in current directory.."<<endl;
          system("pause");
          exit(-1);
      }

      int size = files.size();
      cout<<"there are "<<size<<" image files totally...."<<endl;
      for (int i=0; i<size; i++)
     {
           cout<<files[i].c_str()<<endl;
      }

      system("pause");
      return 0;
}