casting c++,const in class types,function return values...

hi guys!
someone can tell me how can imakeke this thing:?
suppose:
class a
{
public:
int b;
a();
}
a::a(){};

a my;
float b;
//how can I add a casting C++ manner to float wrapped type?
//in practice : how can i perform this:
b = float(my);
???
someone can tell me why-download my program-:
1) if i set NumperoOggetti as static-put this word in the NumeroOggetti class definition- the program can't resolve exteral link and gives so this error?
how do i solve this problem? putting external somewhere ? where?
2) if i set :
class b
{public:
const int a;
b();
}
b::b(){ a = 10; // it doesn't work,a const type value can't
//be changed and so ,how do I initialize it?
//puttng equal sign in the class this way: const int a = 10;
//is not allowed eather. so???
//another question:
-suppose function:

int * pluto()
{
int b=10;
return &b
}
but the adress returned point to the stack?
and so, once the function is executed the stack is popped and the address point to a "deallocated" value?
thanks for any help...
and if you send me an email response [email protected]
THANKS

Quote:

---

someone can tell me how can imakeke this thing:?
suppose:
class a
{
public:
int b;
a();
}
a::a(){};

a my;
float b;
//how can I add a casting C++ manner to float wrapped type?
//in practice : how can i perform this:
b = float(my);
???

---

One way to do this might be like so:

Code:

---

class a
{
public:
    int b;
    int operator()()
    {
        return b;
    }
    a();
}

a::a()
{
}

a my;
my.b = 45;
float b = float(my());  // b should now equal 45.0

---

But then again, if the data member is public, then can't you simply say something like float b = float(my.b); and be done with it.

Quote:

---

2) if i set :
class b
{public:
const int a;
b();
}
b::b(){ a = 10; // it doesn't work,a const type value can't
//be changed and so ,how do I initialize it?
//puttng equal sign in the class this way: const int a = 10;
//is not allowed eather. so???

---

For this you can initialize a const member of a class like this:

Code:

---

class b
{
public:
    const int a;
    b();
};

b::b() : a(10)
{
}

---

Should have put this all in one post but I wasn't sure what you were getting at with the other question so I skipped it at first...

Quote:

---

1) if i set NumperoOggetti as static-put this word in the NumeroOggetti class definition- the program can't resolve exteral link and gives so this error?
how do i solve this problem? putting external somewhere ? where?

---

Somewhere in your source file for the class you must do what is called explicit instantiation of that data member, i.e.

Code:

---

class a
{
public:
    static int iValue;
    static float fValue;
};

int a::iValue;  // You must explicitly instantiate every static class member like this
float a::fValue;

---

Quote:

---

//another question:
-suppose function:

int * pluto()
{
int b=10;
return &b
}
but the adress returned point to the stack?
and so, once the function is executed the stack is popped and the address point to a "deallocated" value?
thanks for any help...

---

Yes... that's true, what's the question?

As for the conversion problem, solve it like this:

Code:

---

class a
{
  float operator float()
  {
    return b;
  }
};

---

thank's guys