problem in operator overloading of >> & << ?

[Tarun Jha]

#include
using namespace std;

const int size = 3;
class vector{
int v[size];

public:
vector(); //constructor num vector
vector(int *x); //constructor from arr
friend vector operator * (int a, vector b); //friend 1
friend vector operator * (vector b, int a); //friend 2
friend istream & operator >> (istream &, vector &); //what is this ??
friend ostream & operator << (ostream &, vector &);
};

in the above code the i am having problem understanding the friend f^n

Quote:

friend istream & operator >> (istream &, vector &);

here's what i know, so istream is for input streaming of data & ostream for output, and does & epresents some kind of reference to function >> ? It is really confusing, please explain. Thank you.

[CPallini]

friend istream & operator >> (istream &, vector &);

That is just for telling the computer the extraction operator (>>) is friend of the vector class. The reference (&) is part of the extraction operator signature, e.g.

istream & operator >> (istream & is, vector & v);

Because such a operator

• takes a reference to istream and a reference to a vector as arguments.
• returns a reference to a istream.

Incidentally this the magic underneath the extraction operator chaining, for instance: cin >> v >> i; -> (cin >> v) >> i; -> cin >> i; -> cin;