sample code fragment to read data from file  (in C)
				/* data in file opened to  FILE *fpin */
                                /* indexing/numbering in Fortran style
                                   starting at 1 */
  fgets(problem_desc, 81, fpin);    /*read character problem description*/
  fscanf(fpin, "%d %d", &neqns, &nnza);




  a_index = (int *) malloc ((neqns+1)*sizeof(int));
  a_struct = (int *) malloc ((nnza+neqns+1)*sizeof(int));


  for (i=0; i <= (neqns); i++){
         fscanf(fpin, "%d", a_index+i);
	 a_index[i] --; /*decrement to match C-style index
                          starting at 0 */ 
  }

  for (i=0; i < (nnza); i++)
          fscanf(fpin, "%d", a_struct+i);
	  a_struct[i] --; /*decrement to match C-style column subscripts
                           0.... neqns-1*/
  }

Note: If Format 2: there are no diagonals 
      If Format 4: there are  diagonals