int main() {
printf("start testing\n");
int from = -100, to = 100;
for (int i = from; i <= to; i++) {
assert(0 - i == negate(i));
assert(((i % 2) == 0) == is_even(i));
assert(i * 2 == multiply_by_two(i));
if (is_even(i)) {
assert(i / 2 == divide_by_two(i));
}
}
for (int i = from;i <= to; i++) {
for (int j = from; j <= to; j++) {
assert(i + j == add_i(i, j));
assert(i - j == subtract(i, j));
assert(i * j == multiply(i, j));
}
}
printf("end testing\n");
return 0;
}
void test_multiply(void)
{
int num = 2;
int result = multiply_by_two(num);
TEST_CHECK_((result == num*2),"ok");
}