C++ fill 2D array [duplicate]

Question

I am Java programmer. I'm trying to fill array in Win32 project

int **Data::matrixInitialize()
{
    int** MX = new int*[n];
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            MX[i][j] = 1;
        }
    }
    return MX;
}

But this code throw an exeption. Please help me to fill 2D array.

Answer 1

You miss an allocation:

int **Data::matrixInitialize()
{
    int** MX = new int*[n];
    for (int i = 0; i < n; i++)
    {
        MX[i] = new int[n]; // Missing line
        for (int j = 0; j < n; j++)
        {
            MX[i][j] = 1;
        }
    }
    return MX;
}

but it would be better to use std::vector or std::array.

Answer 2

Try the following

#include <algorithm>

//...

int **Data::matrixInitialize()
{
    int** MX = new int*[n];

    for ( int i = 0; i < n; i++ )
    {
        MX[i] = new int[n];
        std::fill_n( MX[i], n, 1 );
    }

    return MX;
}