how do I make fstream's >> work for my class?

hi, it's me again :)

I've got a crazy idea, which I am trying to get working. I've coded a class called Float. it looks something like this:

Code:

---

class Float
{
public:
Float();
~Float();

// here come some operators
//...

//at last the value of the float
float Value;
}

---

everything is working fine besides one small detail. When I tried to do something like:

Code:

---

Float SomeFloat;
ifstream SomeFile("my_file");

SomeFile>>SomeFloat;

---

I got a lot of errors. That was really not surprising, since fstream (or, in this case ifstream) hasn't got an operator>> for my class Float.

My question is, can I make fstream (and ifstream) somehow recognize my Float class so that I can simply do SomeFile>>SomeFloat?

At the same time I want to avoid things like:

Code:

---

SomeFile>>SomeFloat.Value;

---

(it looks rather nasty and besides that I want to keep Value protected)

thnx :)

Implement these operators for text-based I/O. They need to be global, not inside your class. However, you might need to make them friends of your class in order to access the internals.
(First the simple version)

Code:

---

std::ostream & operator <<(std::ostream &os, const Float &fl); // Output
std::istream & operator >>(std::istream &is, Float &fl); // Input

---

(And now the full-blow complete version)

Code:

---

template < typename C, class Traits >
std::basic_ostream<C, Traits> & operator <<(std::basic_ostream<C, Traits> &os, const Float &fl); // Output
template < typename C, class Traits >
std::basic_istream<C, Traits> & operator >>(std::basic_istream<C, Traits> &is, Float &fl); // Input

---

Overload the stream extraction operator for your class. Remember to return a reference to an istream.

edit: Foiled again!

thanks a lot, I'll try it out as soon as I come home :)