ignore repeated random indexes of an image

[tina123]

I have an matrix of size 3*3.
and i am interested to pick image indexes randomly.
Therefore, i did like this ...

In the below program,

m = 3, n = 3;
   //random indexes must not be repeated. 
   //Note
   //* [0][1] and [1][0] are different 
   //*  [0][0], [1][1], [2][2], [3][3], [4][4] are symmetrical
  for(int i = 0; i < 9; i++)
  {
	  int RandIndex1 = rand() % m; //generates a random number between row (0 to 5)
	  int RandIndex2 = rand() % n; //generates a random number between column (0 to 5)

	    cout << "[" << RandIndex1 << "," << RandIndex2 << "]" << endl;
  }

but the problem is...
Its possible that the generated RandIndex1 and RandIndex2 are repeated.
Now can i ignore repeated random indexes?