Function By ref How it works

[ahmed106]

#include<iostream>
using namespace std;

double add(double x);
double f(double u);
double u;
double x;
double n;
int main()
{

cout<<"Please enter a number that you want to square\n";
cin>>n;

cout<<"The number you entered is "<<n;
cout<<"\nThe twice of "<<n<< " is "<<add(n);
cout<<"\n";
cout<<"The refference memory adress of this number is..........";
cout<<f(n)<<"\n";// Please explain what this program is doing here. and what is this code.

// the program compiles but I have not understood how this code works






}
double add(double x)

{
return x+x;
}
double f(double u)
{

cout<<&u;



}

[Glandy]

Well this is some deep question you should probably read more about than just my explanation.
However:
When you createa a variable: double u; then there is a field created in your memory (RAM) that is big enough to hold a number of type "double".
when you now write cout << &u;
it shows you in "hexadecimal" (another representation of binary (to the base 16): shorter and easier to read) the exact location of your field inside the memory (RAM). (more precise the address of the first byte of your "double"-field (which is actually 8 byte large).