Dereference pointer to array of long from list iterator - c++

Question

How do I correctly dereference pointers to arrays of long.
In the function main my code seems to print the addresses instead of the long values.
#include <list>
#include <iostream>
#include <cmath>
#include <vector>
bool
is_prime (long i)
{
// fix wrong return values for 0 and 1
if (i <= 1)
return false;
const long j = (long) std::sqrt(i);
for (long k=2; k<j+1; ++k) {
if (i % k == 0)
return false;
}
return true;
}
std::list<long(*)[2]>
goldbach (long number)
{
std::list<long(*)[2]> sums;
std::list<long(*)[2]>::iterator it;
if (number < 4) // Exclude too small integers.
return sums;
if (number % 2) // Exclude uneven numbers.
return sums;
it = sums.begin();
for (long candidate=2; candidate < number; ++candidate)
{
if (is_prime(candidate))
{
if (is_prime(number - candidate))
{
long sum[2];
sum[0] = candidate;
sum[1] = number - candidate;
std::cout << sum[0] << " + " << sum[1] << "\n";
sums.insert(it, &sum);
++it;
}
}
}
return sums;
}
int
main ()
{
std::list<long(*)[2]> sums;
std::list<long(*)[2]>::iterator it;
for(long i = 4; i < 100; i+=2)
{
std::cout << "### " << i << " ###" << "\n";
sums = goldbach(i);
for (it = sums.begin(); it != sums.end(); ++it)
{
long num1 = *((*it)[0]);
long num2 = *((*it)[1]);
std::cout << num1 << " + " << num2 << "\n";
}
std::cout << "\n\n";
}
}

Answer 1

Thanks to the comments I realized that arrays within lists are a bad idea in C++.
I changed my code to the following, which works:
#include <list>
#include <iostream>
#include <cmath>
#include <vector>
bool
is_prime (long i)
{
// fix wrong return values for 0 and 1
if (i <= 1)
return false;
const long j = (long) std::sqrt(i);
for (long k=2; k<j+1; ++k) {
if (i % k == 0)
return false;
}
return true;
}
std::list<std::pair<long, long>>
goldbach (long number)
{
std::list<std::pair<long, long>> sums;
std::list<std::pair<long, long>>::iterator it;
if (number < 4) // Exclude too small integers.
return sums;
if (number % 2) // Exclude uneven numbers.
return sums;
it = sums.begin();
long complement;
for (long candidate=2; candidate < number; ++candidate)
{
if (is_prime(candidate))
{
complement = number - candidate;
if (is_prime(complement))
{
std::pair<long, long> sum = std::make_pair(candidate, complement);
sums.insert(it, sum);
++it;
}
}
}
return sums;
}
int
main ()
{
std::list<std::pair<long, long>> sums;
std::list<std::pair<long, long>>::iterator it;
for(long i = 4; i < 100; i+=2)
{
std::cout << "### " << i << " ###" << "\n";
sums = goldbach(i);
for (it = sums.begin(); it != sums.end(); ++it)
{
std::cout << it->first << " + " << it->second << "\n";
}
std::cout << "\n\n";
}
}