Operator overloading

[namanhams]

Hi,
I'm almost a newbie to C++. I have a problem that i can't figure out. Hope you can help.

I have a class A and i define the operator + for this class, like this :
A operator+ (const A& x, const A& y) { ... }

Then i define operator overloading for << , like this :

ostream& operator<<(ostream& out, A& x ) { ... }

I run
cout << x // x is A object

then it works fine.

The problem is, when i run
cout << x + y // x,y are A object
then it produces error. It says : " no match for operator << ..... "

I dont know why the compiler doesn't recognize x+y as an A object.
Any help ?

[Sopheaktra]

i'm Sopheaktra , Cambodian
Could You please tell me how to overload with opeator New....
Thank...

[a n chatterjee]

no this code is working fine. which compiler are you using ? in Visual Studio 2003 i just ran it. here is the code

 class A
{
public:
	int x; 
	int y;

};

A operator+ (const A& x, const A& y) 
{
	A retObj;
	retObj.x = x.x + y.x;
	retObj.y = x.y + y.y;
	return retObj;
}
ostream& operator<<(ostream& out, A& x ) 
{
	out << x.x << " " << x.y << endl;
	return out;
}

int main()
{
	A a,b,c;
	
	a.x = 5;
	a.y = 10;
	b.x = 4;
	b.y	 = 15;

	c=a+b;	
	cout << c;
	cout << a+b;
}

in case it is problematic, try making both the overloaded operators are member functions, atleast the "<<" one.

[namanhams]

I use g++. I have used your code but it still failed.

[namanhams]

I change
ostream operator<<(ostream& out, A&x)
to
ostream operator<<(ostream&out, A x)

then it works : )

Athough happy , i still dont know why the first doesn't work but when i ignore the '&' then it works ?


Anyone know ?

[Sopheaktra]

Can anyone give me, the g++ compiler.... Post it to [e-mail]
thank...

[Myddrin]

I think it's because your A si not const... personally I use in my class definition :

friend std::ostream& operator<<(std::ostream &out, const A&x);

And it works.

If I remember well, you can't overload the new operator...

[lyecheey]

class Complex {
public:
Complex( double = 0.0, double = 0.0 ); // constructor
Complex operator+( const Complex & ) const; // addition
Complex operator-( const Complex & ) const; // subtraction
void print() const; // output
private:
double real; // real part
double imaginary; // imaginary part
}; // end class Complex

// Constructor
Complex::Complex( double realPart, double imaginaryPart )
: real( realPart ), imaginary( imaginaryPart )
{
// empty body
} // end Complex constructor

// addition operator
Complex Complex::operator+( const Complex &operand2 ) const
{
return Complex( real + operand2.real,
imaginary + operand2.imaginary );
} // end function operator+

// subtraction operator
Complex Complex::operator-( const Complex &operand2 ) const
{
return Complex( real - operand2.real,
imaginary - operand2.imaginary );
} // end function operator-

// display a Complex object in the form: (a, b)
void Complex::print() const
{
cout << '(' << real << ", " << imaginary << ')';
} // end function print

int main()
{
Complex x;
Complex y( 4.3, 8.2 );
Complex z( 3.3, 1.1 );

cout << "x: ";
x.print();
cout << "\ny: ";
y.print();
cout << "\nz: ";
z.print();

x = y + z;
cout << "\n\nx = y + z:" << endl;
x.print();
cout << " = ";
y.print();
cout << " + ";
z.print();

x = y - z;
cout << "\n\nx = y - z:" << endl;
x.print();
cout << " = ";
y.print();
cout << " - ";
z.print();
cout << endl;
return 0;
} // end main

Can anyone tell me how to modify the class to enable input and output of complex numbers through the overloaded >> and << operators, respectively?