Improve on binary converting algorithm (include negative numbers)

I'm doing some C++ array homework. The goals is to convert decimal to binary (include negative numbers). Here's my code, it gets the job done, but I would like to see if anything can be improved, or any better algorithm (using binary shift maybe?).

#include <iostream> 
using namespace std;
// doi tu thap phan sang nhi phan
void decToBinary(int n, int nhiphan[])
{
    for (int i=0; i < 16; i++)
    {
        // to binary
        nhiphan[i] = n % 2;
        n = n / 2;
    }
    // inverse array
    for (int i = 0, j = 15; i < j; i++, j--)
    {
        int temp = nhiphan[i];
        nhiphan[i] = nhiphan[j];
        nhiphan[j] = temp;
    }
}
void reverse(int& a)
{
    if (a == 0)
        a++;
    else a--;
}

void outArr(const int a[], int size) {
    for (int i = 0; i < size; ++i)
        cout << a[i];
}

int main()
{
    int nhiphan[16];
    int n;
    do {
        cout << "Nhap so (-255 <= n <= 255) chuyen doi sang nhi phan (16 bit): ";
        cin >> n;
    } while (n > 255 || n < -255);
    if (n < 0) {//check negative
        n *= -1;
        decToBinary(n, nhiphan);
        for (int i = 0; i < 16; i++)// 1's complement
            reverse(nhiphan[i]);
        // +1
        if (nhiphan[15] == 0)//2's complement
            nhiphan[15] = 1;
        else 
        { 
            nhiphan[15] = 0; 
            int i = 15;
            do {
                reverse(nhiphan[i-1]);
                i--;
            } while (nhiphan[i-1] == 0);
        }
    }
    else decToBinary(n, nhiphan);
    outArr(nhiphan, 16);
    return 0;
}