Question

I am making a Sudoku program and my i have a test.txt file that reads

53__7____    
6__195___
_98____6_
8___6___3
4__8_3__1
7___2___6
_6____28_
___419__5
____8__79

where the “_” are actually spaces. The reason i give you _ is so you can see that there are literally only 9 characters on each line.

I was thinking that I would have to do something like having GRID[row][column], however I frankly don’t know what types I should put my arrays as and I am just lost.

I simply want to make it so when i want to output say GRID[0][0] it returns 5, while if i ask for GRID[0][3] it returns a ‘ ‘.

It is getting it so the array store both the numbers and the spaces is where i am getting completely lost

What I currently have tried so far:

int main()
{
 ifstream myfile(test.txt);
 string line;
 char sudoku_grid[9][9];

 if (myfile.is_open())
 {
  while(myfile.good())
   {
    getline(myfile, line);
    cout << sudoku_grid[line] << endl;
   }
   myfile.close();
  }
 else cout << "error";
 return 0;
}

it returns the error line 12: no match for ‘operator [ ]’ in ‘sudoku_grid[line]’

Here is my attempt though guidelines through you guys:

int main()
{
 ifstream myfile(test.txt);
 string line;
 char sudoku_grid[9][9];

 if (myfile.good())
 {
  for(int i = 0; i < 9; i++)
   {
    getline(myfile, line);
    for(int j = 0; j < 9; j++)
       {
       if (line[j] == ' ')
          sudoku_grid[j][i] = -1;
       else  sudoku_grid[j][i] = line[i];
       }
    cout << sudoku_grid[i] << endl;
   }
   myfile.close();
  }
 else cout << "error";
 return 0;
}

The result is a very awkward answer of strange letters and a new numbers.

Answer 1

Since you need to store both chars and integer type values, use char. each of your integer lies in the range 0-9, so can be stored as a character.

char Grid[9][9];

now you can read each character from the string and store it in the array. It will not only keep your spaces intact but also each character. Always remember to use ASCII codes to access the elements of the grid. For 0-9, ASCII codes are 48-57, ASCII code for space is 32.

Hope it helps…

Edit code: Here is the simplest example… PLace your test file in d:, or edit the path of file in code

int main (void)
{
    FILE    *fp = fopen("d:\\test.txt","r");
    char sudoku_grid[9][9], ch;
    // I am assuming that file is valid and data in that is also valid
    if(fp)
    {
        for(int i = 0; i < 9; i++)
        {            
            for(int j = 0; j < 9; j++)
            {
                //too read each character
                ch = fgetc(fp);
                sudoku_grid[i][j] = ch;   
            }
            // to read '\n' from the line
            ch = fgetc(fp);
        }
//for checking if data went correctly
        for(int i = 0; i< 9;i++)
        {
            for(int j= 0; j<9;j++)
                cout<<sudoku_grid[i][j];
            cout<<endl;
        }
    }


 return 0; 
}