Use of undeclared identifier and expected expression error. Xcode - c++

Question

So I am completely new to C++ and attempting to use Xcode to write this code that analyzes two integers. I keep getting an error on the "if" line that says "use of undeclared identifier x, and "use of undeclared identifier y" I also get an error on the "else" line that says "Expected expression". What do I need to do/change to make this program work? Help.
#include <iostream>
using namespace std;
void swap (int &x, int &y);
int main()
{
cout << "Please enter two integers:/n";
cout << "First integer ==> " " >> x >> ";
cout << "Second integer ==> " " >> y >> ";
cout << endl;
if ( &x < &y )
cout << "Your integers are in the correct order:/n";
cout << " << x << " " << y << ";
else void swap(int &x, int &y);
cout << "Your integers have been swapped:/n";
cout << " << x << " " << y << ";
}

Answer 1

The variables x and y do not exist in the scope of the function main.
You just declared those variables in the function declaration swap, and happen to name those variables x and y. That's what these errors mean. The variables do not exist in the current scope.
use of undeclared identifier x
use of undeclared identifier y
You also do not ever define that function, so you are likely name-shadowing the std version of swap.

Answer 2

You need to declare and assign x and y inside a function (or outside) that refers to the values:
for example
int main()
{
int x = 5, y = 10;
if ( &x < &y )
cout << "Your integers are in the correct order:/n";
cout << " << x << " " << y << ";
else void swap(int &x, int &y);
//...
}
edit:
#include <iostream>
using namespace std;
void swap (int &x, int &y);
int main()
{
int x = 0, y = 0;
cout << "Please enter two integers:/n";
cout << "First integer ==> " " >> x >> ";
cout << "Second integer ==> " " >> y >> ";
cout << endl;
if ( x < y )
{
cout << "Your integers are in the correct order:/n";
cout << " << x << " " << y << ";
}
else
{
swap(int &x, int &y);
cout << "Your integers have been swapped:/n";
cout << " << x << " " << y << ";
}
return 0;
}
void swap (int &x, int &y)
{
// define here
}