Indices of even numbers

#include <iostream>
#include <vector>
using namespace std;

// Take a list of numbers and return the indices of the even numbers.

// This function takes an integer and returns
// true if it is even. Otherwise, it returns false.
int is_even(int number)
{
    // If two divides into the number evenly
    if (number % 2 == 0)
    {
        // The number is even.
        return true;
    }
    else // Otherwise,
    {
        // The number is odd.
        return false;
    }
}

// This function takes a list of numbers and returns
// the indices of the even numbers.
vector<int> get_even_numbers(vector<int>& number_list)
{
    // These are the indices of the even numbers.
    vector<int> even_number_indices;

    // We are testing this number.
    int current_number;

    // Go from the beginning to the end of the number list.
    for (size_t i = 0; i < number_list.size(); ++i)
    {
        // Test the next number.
        current_number = number_list[i];

        // If the number is even,
        if (is_even(current_number))
        {
            // Add its index to the new list.
            even_number_indices.push_back(i);
        }
    }

    return even_number_indices;
}

int main()
{
    // Create a list of numbers.
    vector<int> numbers = { 1, 2, 3, 12, 24, 14, 19, 30 };

    // Get a list of the even numbers.
    vector<int> even_numbers = get_even_numbers(numbers);

    // Display the even numbers.
    for (size_t i = 0; i < even_numbers.size(); ++i)
    {
        cout << even_numbers[i] << endl;
    }

    return 0;
}