function for 2d dynamic array
int ** two_dim_array(int row_num, int col_num) { int **two_dim_array=(int **)malloc(sizeof(int *)*row_num); int i, j; for(i=0:i<row_num;i++) { two_dim_array[i]=(int *)malloc(sizeof(int)*col_num); for(j=0:j<col_num;j++) two_dim_array[i][j]=0; } return two_dim_array; }