Input and rotate a grid through designated input format and file import

grid_file.cpp

/*********************************************************************
 *  Compilation:  g++ grid_file.cpp -o grid_file.exe
 *  Execution:    grid_file.exe input.txt
 *  
 *  Input and rotate a grid
 *  
 *  This is a toy code snippet for handling informational
 *  input (integer size of grid), importing multiple
 *  columns, and exporting with formatted output. This
 *  example uses C++ approaches to file and string input
 *  processing as compared to the grid.cpp example that
 *  solely uses standard input.
 *  
 *  $ cat input.txt
 *    3
 *    NW N NE
 *     W 0  E
 *    SW S SE
 *
 *  $ grid_file.exe input.txt
 *    NW  W SW
 *     N  0  S
 *    NE  E SE
 *********************************************************************/
 
#include <iostream> // std::cout, std::cin, std::right, std::endl
#include <string>   // std::string
#include <iomanip>  // std::setw
#include <fstream>  // std::ifstream
#include <cstdlib>  // atoi
#include <sstream>  // std::stringstream

int main(int argc, char* argv[])
{
    int N;
    
    if (argc != 2) return 1;

    std::ifstream in(argv[1]);
    std::string line;
    
    std::getline(in, line);
    N = atoi(line.c_str());
    
    std::string arr[N][N];

    for(int i=0; std::getline(in, line); ++i)
    {
        std::stringstream ss(line);
        std::string a, b, c;
        ss >> a >> b >> c;
        arr[i][0] = a;
        arr[i][1] = b;
        arr[i][2] = c;
    }
    
    for (int i = 0; i < N; ++i)
    {
        for (int j = 0; j < N; ++j)
        {
            std::cout << 
            std::right << 
            std::setw(2) << 
            arr[j][i] << " ";
        }
        std::cout << std::endl;
    }
    
    return 0;
}