程序代码：

#define d_array_init_size 10
#define d_array_size_increment 10

typedef int elem_type;

typedef struct {
    elem_type * element;
    int size;
    int length;
} d_array

int init_d_array(d_array a) {
    a.element = elem_type * malloc(sizeof(int) * d_array_init_size);
    if (!a.element) {
        return 1;
    }
    a.size = d_array_init_size;
    a.length = 0;
    return 0;
}

int extend_d_array(d_array a) {
    a.element = elem_type * realloc(a.element, a.length + d_array_size_increment);
    if (!a.element) {
        return 1;
    }
    a.size += d_array_size_increment;
    return 0;
}

int free_d_array(d_array a) {
    free(a.element);
    a.element = NULL;
    a.size = 0;
    a.length = 0;
    return 0;
}