g.c

#include <stdlib.h>
#include <stdio.h>

struct Point {
	int x;
	int y;
	int z;
};

struct Segment {
	struct Point *p1;
	struct Point *p2;
};

struct Segment *segment(struct Point *p1) {
	// Create a new point symmetrical to 0yz
	struct Point *p2 = malloc(sizeof(struct Point));
	p2->x = -p1->x;
	p2->y = p1->y;
	p2->z = p1->z;

	// Create a segment
	struct Segment *s = malloc(sizeof(struct Segment));
	s->p1 = p1;
	s->p2 = p2;

	return s;
}

int main(void) {

	struct Point *p = malloc(sizeof(struct Point));
	p->x = 1;
	p->y = 2;
	p->z = 3;

	struct Segment *s = segment(p);

	printf("components\n");
	printf("p1: x=%d; y=%d; z=%d\n", s->p1->x, s->p1->y, s->p1->z);
	printf("p2: x=%d; y=%d; z=%d\n", s->p2->x, s->p2->y, s->p2->z);

	return 0;
}