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

#define print_vec(vec) for (int i = 0; i < (vec)->size; ++i) { printf("%d, ", (vec)->data[i]); } printf("\n")

struct vec {
	int size;
	int *data;
};


struct vec* new(unsigned int n);
struct vec* add(const struct vec *v, const struct vec *w);
struct vec* smul(double s, const struct vec *v);

int main(void)
{
	struct vec *v = new(4);
	v->data[0] = 1;
	v->data[1] = 2;
	v->data[2] = 3;
	v->data[3] = 4;
	print_vec(v);

	struct vec *w = new(4);
	w->data[0] = 5;
	w->data[1] = 6;
	w->data[2] = 7;
	w->data[3] = 8;
	print_vec(w);

	struct vec *added = add(v, w);
	print_vec(added);

	struct vec *multiplied = smul(3, v);
	print_vec(multiplied);
}

struct vec* new(unsigned int n){
	struct vec* ret = malloc(sizeof(struct vec));
	ret->size = n;
	ret->data = malloc(sizeof(int) * n);
	return ret;
}


struct vec* add(const struct vec *v, const struct vec *w){
	if(v->size != w->size)
		return NULL;
	struct vec *ret = new(v->size);
	for (int i = 0; i < v->size; ++i) {
		ret->data[i] = v->data[i] + w->data[i];
	}
	return ret;
}
struct vec* smul(double s, const struct vec *v){
	struct vec *ret = new(v->size);
	for (int i = 0; i < v->size; ++i) {
		ret->data[i] = v->data[i] * s;
	}
	return ret;
}