Outputting Values from a 2D Array to a Text File - c++

Question

I am writing some C++ code and i currently have a function that reads in some numbers from a text file and stores them into a 2D array. I now need to output the same numbers i have stored into the 2D array back out into a new text file. I currently have some code in a function that can output the numbers however they are not in the same format as the input file. As you can see below.
Input File Format (space between each number)
1 2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9 1
3 4 5 6 7 8 9 1 2
4 5 6 7 8 9 1 2 3
5 6 7 8 9 1 2 3 4
6 7 8 9 1 2 3 4 5
7 8 9 1 2 3 4 5 6
8 9 1 2 3 4 5 6 7
9 1 2 3 4 5 6 7 8
Output File Format Currently
123456789234567891345678912456789123567891234678912345789123456891234567912345678 (this is all on one line)
My function to read in from the text file.
void Grid::LoadGrid(const char filename[])
{
ifstream file(filename);
for (int y = 0; y < 9; y++) {
for (int x = 0; x < 9; x++)
{
file >> m_grid[x][y];
}
}
file.close();
}
My function to read out to the text file. (m_grid is the 2D array)
void Grid::SaveGrid(const char filename[])
{
ofstream file(filename);
for (int y = 0; y < 9; y++) {
for (int x = 0; x < 9; x++)
{
file << m_grid[x][y];
}
}
file.close();
}
If anyone can help me output it to the text file so it will appear the same as the input i'd be very grateful.
Edit: Question has been answered.

Answer 1

After your inner loop completes
file << endl;
Also in your inner loop might want to..
file << m_grid[x][y] << " ";

Answer 2

Update the way you write to the file like this:
void Grid::SaveGrid(const char filename[])
{
ofstream file(filename);
for (int y = 0; y < 9; y++) {
cout << endl;
for (int x = 0; x < 9; x++)
{
cout << m_grid[x][y];
cout << " ";
}
}
file.close();
}

Answer 3

In your output function you should write the spaces after each character. And the newline character when you reach the end of a row.
I believe this would work
void Grid::SaveGrid(const char filename[])
{
ofstream file(filename);
for (int y = 0; y < 9; y++)
{
for (int x = 0; x < 9; x++)
{
file << m_grid[x][y] << " ";//write a space after the character
if(x ==8) //at x ==8 is where this for loop would exit
{
file << "\n"
}
}
file.close();
}

Answer 4

The output you are seeing is exactly what you told the compiler to do. You are displaying each of your NxN matrix elements one right after another. You never added any white space to your output stream. To fix this, it is quite simple. Adjust your function as follows:
void Grid::SaveGrid(const char filename[])
{
ofstream file(filename);
for (int y = 0; y < 9; y++) {
for (int x = 0; x < 9; x++)
{
file << m_grid[x][y] << " "; // and a space after each element
}
file << '\n'; // add a new line character after each row has been printed.
}
file.close();
}
Here's a simple working example that uses a std::vector<int> of your numbers and displays it to the console. The only difference here is that I'm using a 2D to 1D mapping for the indexing into the vector. Once you understand how this affects the formatting it should be trivial to convert it from an std::vector to a multidimensional array and to convert the iostream to a fstream output.
#include <iostream>
#include <vector>
int main() {
const std::vector<int> values{ 1,2,3,4,5,6,7,8,9,
2,3,4,5,6,7,8,9,1,
3,4,5,6,7,8,9,1,2,
4,5,6,7,8,9,1,2,3,
5,6,7,8,9,1,2,3,4,
6,7,8,9,1,2,3,4,5,
7,8,9,1,2,3,4,5,6,
8,9,1,2,3,4,5,6,7,
9,1,2,3,4,5,6,7,8
};
const int size = 9;
for (int row = 0; row < 9; row++) {
for (int col = 0; col < 9; col++) {
std::cout << values[col + size*row] << " ";
}
std::cout << '\n';
}
return 0;
}
-Ouput-
1 2 3 4 5 6 7 8 9
2 3 4 5 6 7 8 9 1
3 4 5 6 7 8 9 1 2
4 5 6 7 8 9 1 2 3
5 6 7 8 9 1 2 3 4
6 7 8 9 1 2 3 4 5
7 8 9 1 2 3 4 5 6
8 9 1 2 3 4 5 6 7
9 1 2 3 4 5 6 7 8