c实现ls功能，打印一个目录下的文件

#include <dirent.h>
#include <stdio.h>
int main(int argc, char* argv[]) {
  DIR *dp;
  struct dirent *dirp;
  if ( argc != 2) {
      //err_quit("usage: ls directory_name");
      printf("usage: ls directory_name");
  }
  if ((dp = opendir(argv[1])) == NULL) {
    //err_sys("can`t open %s", argv[1]);
    printf("can`t open %s", argv[1]);
  }
  while ((dirp = readdir(dp)) != NULL)
  {
    printf("%s\n", dirp->d_name);
  }
  closedir(dp);
  //exit(0);
  return 0;
}