C++ reading 2d array from file -

i have small problem. trying read file, , output read data 2d array in c++. i've created .txt file , been fixing code not find out problem is.

my code following:

#include <iostream> #include <fstream> // file handleing  using namespace std;  int sudoku[9][9];  int main() {     ifstream fp("sudoku.txt");     // reading , opening existing file sudoku.txt     for(int row = 0; row < 9; row++){         for(int column = 0; column < 9; column++){             fp >> sudoku[row][column];             // fp read characters         }     }     for(int row = 0; row < 9; row++){         for(int column = 0; column < 9; column++){             cout << sudoku[row][column] << " ";         }         cout << endl;     }     fp.close();     return 0; 

my text file looks this:

6 4 0 0 0 0 8 0 1 5 0 0 7 0 0 0 2 0 2 7 0 4 9 0 0 0 0 0 3 6 5 1 8 0 9 0 0 0 0 3 0 2 0 0 0 0 5 0 9 6 7 1 4 0 0 0 0 0 7 4 0 8 6 0 8 0 0 0 9 0 0 2 7 0 1 0 0 0 0 5 9 

my first question: in previous version, array defined inside main function. got trash output instead of content of file. don't understand this: have define sudoku array outside main function in order not wrong values stored in elements, , why ?

my second question: output of current code lots of zeros. expected find elements read file. don't understand either. doing wrong? i've tried search answer i'm attempting write part of sudoku solver , i'm stuck.

the 2 problems linked, , it's related problemm file reading:

• in first case garbage, because local array not initialized. file reading fails, garbage remains.
• in second case 0 because global array has static storage type, , it's 0 initialized before use of it.

better keep variables local unless obliged to otherwise. have check if ifstream fp(...); open file or if there's problem:

ifstream fp("sudoku.txt"); if (! fp) {     cout << "error, file couldn't opened" << endl;      return 1;  }     for(int row = 0; row < 9; row++) {  // stop loops if nothing read    for(int column = 0; column < 9; column++){         fp >> sudoku[row][column];         if ( ! fp ) {            cout << "error reading file element " << row << "," << col << endl;             return 1;          }     } } 

it may executable executed working directory think.