2d array pointers...

[ande6870]

am i doing this right? im assigning random values to Matrix a & b using a pointer, then trying to print out the first value in matrix a...not doing something right, i am getting segmentation fault

#include <iostream>
#include <stdlib.h>
using namespace std;

const int SIZE = 100;
typedef double Matrix[SIZE][SIZE];

int main()
  {
    Matrix *a;
    Matrix *b;
    Matrix *c;
    for (int i = 0; i < SIZE; i++)
      {
        for (int j = 0; j < SIZE; j++)
          {
            srand(time(NULL));
            *a[i][j] = rand() % 100;
            *b[i][j] = rand() % 100;
          }
      }
    cout << *a[0][0] << endl;
  }

[ande6870]

compiles fine, just won't run

[Peter87]

Is there a reason why you use pointers here? Try without.

[humyunfuad]

as you use srand() function you should include #include<ctime> ..

[Stewbond]

I think you need to put the [SIZE] beside the variables, not the type.

#include <iostream>
#include <stdlib.h>
using namespace std;

const int SIZE = 100;
typedef double Matrix;

int main()
  {
    srand(time(NULL));
    Matrix *a[SIZE][SIZE];
    Matrix *b[SIZE][SIZE];
    Matrix *c[SIZE][SIZE];
    for (int i = 0; i < SIZE; i++)
      {
        for (int j = 0; j < SIZE; j++)
          {
            *a[i][j] = rand() % 100;
            *b[i][j] = rand() % 100;
          }
      }
    cout << *a[0][0] << endl;
  }

If you want to avoid rewriting size over and over, you could make a struct:

#include <iostream>
#include <stdlib.h>
using namespace std;

const int SIZE = 100;
struct Matrix
  {
    double matrix[SIZE][SIZE];
  };

int main()
  {
    srand(time(NULL));
    Matrix *a;
    Matrix *b;
    Matrix *c;
    for (int i = 0; i < SIZE; i++)
      {
        for (int j = 0; j < SIZE; j++)
          {
            *a.matrix[i][j] = rand() % 100;
            *b.matrix[i][j] = rand() % 100;
          }
      }
    cout << *a.matrix[0][0] << endl;
  }

Oh, it doesn't cause your problem, but it will cause problems:
Put srand at the top of main. It needs to be called exactly once in a code. Any more and you'll start to see non-random behavior.

[ande6870]

sweet thanks lol