Thread: Reading from a text file with stdin

Hello, my project asks that I read input from stdin that allows redirection from a text file. Then redirect the output to a different file using stdout . It mentions that can't use file operations to read the input. The text file I have is an 9x9 array of characters separated by spaces. I already set up a code that will convert it to a 2D array. But I'm not sure how to do the input/output correctly, currently I am using ifstream for reading the file.
(Sorry for the mess of a code)

Code:

#include <iostream>
#include <string>
#include <sstream>
#include <fstream>
#include <vector>
#include <array>
using namespace std;
int main()
{

 
    //Open text file
   ifstream file("letters.txt");

    string line;
    int row = 0;
    int col;
    char array[25][25];
    // Insert each character into array
    while (getline(file, line))
    {
        istringstream iss(line);
        char value;
        col = 0;

        while (iss >> value)
        {
            array[row][col] = value ;
            col++;
        }
        row++;
    }



    cout << "********PRINT OUTPUT******" << endl;
    for (int i = 0; i < row; ++i)
        {
            for (int j = 0; j < col; ++j)
            {
                cout << array[i][j] << ' ';
            }
            cout << endl;
        }
   
}