How do I print this matrix defined with pointers? PLEASE HELPPP

I defined this matrix with pointers, but I couldn't figure out how to print like a normal matrix print. like :

Code:

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for (i = 0; i < row; i++)
        {
                for (j = 0; j < col; j++)
                        cout << M[i][j] << "\t";


                cout << "\n";
        }

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/////////////////////MY CODE/////////////////////////////

Code:

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#include<iostream>
#include<math.h>
#include<time.h>
using namespace std;
#define SIZE 20


void print_matrix2(int M[][SIZE], int a);


int main() {
        int M[SIZE][SIZE] = {};
        int N[SIZE][SIZE] = {};
        int P[SIZE][SIZE] = {};
        int* ptrMatris = &M[0][0];
        int* ptrMatris2 = &N[0][0];
        int* ptrMatris3 = &P[0][0];
        int size, a,i;
        srand(time(NULL));


        cout << "enter size: " << endl;
        cin >> size;


        a = sqrt(size);


        for (i = 0;i < size;i++)
        {
                *(ptrMatris+i) = rand() % 11;
                *(ptrMatris2 + i) = rand() % 11;
        }
       
       
        /*cout << "----MATRIX - 1----" << endl;
        print_matrix2(M, a);
        cout << endl;
        cout << "----MATRIX - 2----" << endl;
        print_matrix2(N, a);
        cout << endl;
        */
       
        system("pause");
}


void print_matrix2(int M[][20],int a)
{
        int i, j;
        for (i = 0; i < a; i++)
        {
                for (j = 0; j < a; j++)
                        cout << M[i][j] << "\t";


                cout << "\n";
        }
}

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I've been trying to solve this problem for 2 days but I couldn't find it. Please help!!!!!!

You've "flattened" your matrix into a vector, so if you want to print the vector as a matrix again, you need to compute the index of each entry in the matrix. It seems like a waste of effort when you can directly use the 2D array as the matrix.

yes I think you are right. So how do I get the product of two matrices in this way with the help of pointers?

Quote:

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Originally Posted by laserlight

You've "flattened" your matrix into a vector, so if you want to print the vector as a matrix again, you need to compute the index of each entry in the matrix. It seems like a waste of effort when you can directly use the 2D array as the matrix.

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> int M[SIZE][SIZE]
You have a block of memory that looks like this, if you were to subscript it.
In actuality, it's all just one contiguous block of SIZE*SIZE*sizeof(int) bytes.

This is what it looks like for SIZE=10

Code:

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..........
..........
..........
..........
..........
..........
..........
..........
..........
..........

---

> cin >> size;
> a = sqrt(size);
OK, say you input 9 for size, so a will be 3.
Then run your loops.

If you flatten the matrix, this is what you get in memory.

Code:

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RRRRRRRRR.
..........
..........
..........
..........
..........
..........
..........
..........
..........

---

If you didn't flatten it, you would have this instead.

Code:

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RRR.......
RRR.......
RRR.......
..........
..........
..........
..........
..........
..........
..........

---

Now this is something you could just pass to
void print_matrix2(int M[][20],int a)
without any further effort.

So why can't you do this in main?

Code:

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for (i = 0; i < a; i++)
        for (j = 0; j < a; j++)
                M[i][j] = rand() % 11;

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