Unix環境高度プログラミング1

#include 
#include 
#include 

using namespace std;

int main( int argc, char* argv[] )
{
        DIR *dp;
        struct dirent *dirp;
        if(argc != 2)
        {   
                cout << "a single argument (the directory name) is required" << endl;
                return 0;
        }   
        if( (dp=opendir(argv[1])) == NULL)
        {   
                cout << "can't open " << argv[1] << endl;
                return 0;
        }   
        while( (dirp = readdir(dp)) != NULL)
        {   
                cout << dirp->d_name << endl;
        }   
        closedir(dp);
        return 0;    
}