#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>

#define NUMMAX 1000
#define LENMAX 50

char filename[NUMMAX][LENMAX+1]={{0}};

int qsort_strcmp(const void *a, const void *b){
    return strcmp((char*)a, (char*)b);
}

int main(){
    struct dirent *de;
    int i,j;
    DIR *dir;
    i=0;
    dir=opendir("/bin");
    for(de=readdir(dir);de;de=readdir(dir)){
        if(strcmp(de->d_name,".")&&strcmp(de->d_name,"..")){
            strncpy(filename[i++],de->d_name,LENMAX);
        }
    }
    closedir(dir);
    qsort(filename,i,LENMAX+1,qsort_strcmp);
    for(j=0;j<i;j++){
        puts(filename[j]);
    }
    return 0;
}