istream example

#include <iostream>
using namespace std;

class thing{
    double something;
    public:
    thing(double d) : something(d) {}; //constructor with member initialization list
    friend istream& operator>>(istream&,thing&); //the istream operator overloading
};

istream& operator>>(istream& in,thing& t) //the definition of the operator overloading (global)
{
    cout << "Write a number: "; //first we just write something to the user
    //you can do other thing in here as well (similarly to ostream), for example check the correctness of the entered data...
    in >> t.something;  //then read it from in to something
    return in; //finally return with the istream
}


int main ()
{
    thing t(5.5);
    cin >> t;
    return 0;
}