typedef struct {
	int day, month; } DateT;
typedef struct {
	int hour, minute; } TimeT;
typedef struct {
	char plate[7]; double speed; DateT d; TimeT t; } TicketT;

TicketT *tickets;
tickets = malloc(1000 * sizeof(TicketT));
assert(tickets != NULL);

float **matrix;

// allocate memory for m pointers to beginning of rows
matrix = malloc(m * sizeof(float *));
assert(matrix != NULL);

// allocate memory for the elements in each row
int i;
for (i = 0; i < m; i++) {
   matrix[i] = malloc(n * sizeof(float));       
   assert(matrix[i] != NULL);
}