Improve on binary converting algorithm (include negative numbers) - c++

Question

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;
}