Declaring and accessing 2D array

Question

How can I use array pointer (int *) to create and print this kind of 2d array:

0 1 2 3 4 5 6 7 8...
1 2 3 4 5 6 7 8 9...
2 3 4 5 6 7 8 9 10...
3 4 5 6 7 8 9 ...
4 5 6 7 8 9...
5...

I currently have this code:

#include <stdio.h>
#include <stdlib.h>

void createMatrix(int * matrix, int row, int column)
{
    puts("Begin creating matrix.");
    int i, j;
    for(i = 0; i < row; i++)
    {
        for(j = 0; j < column; j++)
        {
            *(matrix) = i + j;
            matrix++;
        }
    }
    puts("Success!");
}

int printMatrix(int * matrix, int row, int column)
{
    puts("Begin printing matrix!");
    int i, j, valuesPrinted;
    for(i = 0; i < row; i++)
    {
        for(j = 0; j < column; j++)
        {
            printf("%5d ", *(matrix + i * j));
            valuesPrinted++;
        }
        puts("");
    }
    puts("Printing success!");
    return valuesPrinted;
}

int main()
{
    int row = 11;
    int column = 13;
    int * matrix = malloc(sizeof(int) * row * column);

    createMatrix(matrix, row, column);
    printMatrix(matrix, row, column);
    return 0;   
}

What I want to do is: use declare array and assign to pointer, then pass the pointer to a function and give it values as above. I think the problem is in the way I initialize the 2D array by pointer and access it.

And the result is:

    0     0     0     0     0     0     0     0     0     0     0     0     0
    0     1     2     3     4     5     6     7     8     9    10    11    12
    0     2     4     6     8    10    12     2     4     6     8    10    12
    0     3     6     9    12     3     6     9    12     3     6     9    12
    0     4     8    12     4     8    12     4     8    12     4     8    12
    0     5    10     3     8    13     6    11     4     9    14     7    12
    0     6    12     6    12     6    12     6    12     6    12     6    12
    0     7     2     9     4    11     6    13     8    15    10    17    12
    0     8     4    12     8     4    12     8    16    12     8    16    12
    0     9     6     3    12     9     6    15    12     9    18    15    12
    0    10     8     6     4    14    12    10     8    18    16    14    12

Answer 1

int *matrix = malloc(sizeof(int) * row * column);
// could better be written as
int *matrix = malloc((row*column) * sizeof *matrix);

The above statement dynamically allocates an array of integers of size row * column. If you want to access the elements of this array as you would access elements of a 2D array, then the element at row i and column j has the index

i * column + j

Modify your printMatrix function to -

int printMatrix(int * matrix, int row, int column)
{
    puts("Begin printing matrix!\n");
    int i, j, valuesPrinted;
    for(i = 0; i < row; i++)
    {
        for(j = 0; j < column; j++)
        { 
            // this is equivalent and more readabable
            // printf("%5d ", matrix[i*column + j]);
            printf("%5d ", *(matrix + i*column + j));
                                      //  ^ note i is multiplied by column
            valuesPrinted++;
        }
        puts("");
    }
    puts("Printing success!\n");
    return valuesPrinted;
}

Answer 2

printf("%5d ", *(matrix + i * column + j));

instead of

printf("%5d ", *(matrix + i * j));

Answer 3

Your printing code is using the wrong expression to access the elements of the matrix. You've got:

printf("%5d ", *(matrix + i * j));

You need:

printf("%5d ", *(matrix + i * column + j));

Or:

printf("%5d ", matrix[i * column + j]);