How can this code be implemented without the string library?

Question

C++ / C#

Without string
And without deff of course

#include <iostream>
#include <fstream>
#include <string>


using namespace std;
int main()
{
  string i, q;
  ifstream z("onefile.txt"), d("twofile.txt");
  while (getline(z, i) && getline(d, q))
  {
    if (i != q)
      cout << i << endl << q << endl;
  }
}

Answer 1

Get char arrays of some sufficient length. Read through gets_s. Compare strings with strcmp.