c++ scandir 按顺序读取文件目录

#include <dirent.h>
#include <string>
#include <iostream>
#include <unistd.h>

using namespace std;

int fileNameFilter(const struct dirent *cur)
{
    std::string str(cur->d_name);
    if (str.find(".jpg") != std::string::npos)
    {
        return 1;
    }
    return 0;
}

int main()
{
    while(1)
    {
        struct dirent **namelist;
        int n = scandir(".", &namelist, fileNameFilter, alphasort);

        if(n < 0)
            cerr << "memery error " << endl;
        else 
            cout << "total number is: " << n << endl;
            
        for( int i = 0; i < n; i++)
        {
            // /* skip . && .. */
            // if(namelist[i]->d_name[0] == '.')
            //     continue;

            cout<<namelist[i]->d_name<<endl;
            free(namelist[i]);
        }
        free(namelist);
        sleep(5);
    }

    return 0;
}