#include <stdio.h>
 
typedef struct {
	int x, y;
	void(*show)();
} point_t;
 
point_t *global_point_ptr;
 
void point_show() {
	point_t point = *global_point_ptr;
	printf("x = %d, y = %d\n", point.x, point.y);
}
 
point_t point(int x, int y) {
	point_t r = { x, y, point_show };
	return r;
}
 
point_t *use_point(point_t *p) {
	global_point_ptr = p;
	return p;
}
 
 
 
int main(void) {
	point_t a = point(2, 10);
	point_t b = point(-10, 5);
 
	use_point(&a)->show();
	use_point(&b)->show();
 
	return 0;
}
 

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