i want to know how does this work the logic behind it

Question

I have this program that calculate the total of the even and the odd:

#include <iostream>
#include <vector>

using namespace std;

int main() {

int even_total = 0;
int odd_product = 1;

std::vector<int> vector = {2, 4, 3, 6, 1, 9};

for (int i = 0; i < vector.size(); i++) { //what is the i < vector.size() for

if (vector[i] % 2 == 0) {

even_total = even_total + vector[i]; //how does this work

} else {

odd_product = odd_product * vector[i]; //how does this work

}

}

std::cout << "sum of even: " << even_total << "\n";
std::cout << "product of odd: " << odd_product << "\n";

return 0;
}

and the when i hit run i get:
sum of even: 12
product of odd: 27

//can some one tell me why is this the answer i know that i am so stupid but i would really appreciate your help :)

Answer 1

the total even = 2 + 4 + 6 = 12
the odd_product = 3 * 1 * 9 = 27

Answer 2

but why are we multiplying for the the odd and can you please tell me what does the i in the [] stand for and it's function

Answer 3

There no special reason for multipyling the odd numbers. The "I" in [] is your basic array notation to access the vector elements in the for loop.