Operator overloading << error: must take exactly one argument

[nomiz]

Hi all!

I can't get my head around the compile error I get when overloading the << operator:
error: ‘QDataStream& Coordinate:perator<<(QDataStream&, const Coordinate&)’ must take exactly one argument

Here is the code:

coordinate.h:

class Coordinate
{
public:
    Coordinate();
 
    double x, y, z;
 
    // output
    QDataStream &operator <<(QDataStream& out, const Coordinate& c);
};

class Coordinate
{
public:
    Coordinate();

    double x, y, z;

    // output
    QDataStream &operator <<(QDataStream& out, const Coordinate& c);
};

To copy to clipboard, switch view to plain text mode 

coordinate.cpp:

#include "coordinate.h"
 
Coordinate::Coordinate()
{
    x = y = z = 0.;
}
 
QDataStream& operator <<(QDataStream& out, const Coordinate& c)
{
    out <<  "(" <<  c.x << ", " << c.y << ", " << c.z << ")";
    return out;
}

#include "coordinate.h"

Coordinate::Coordinate()
{
    x = y = z = 0.;
}

QDataStream& operator <<(QDataStream& out, const Coordinate& c)
{
    out <<  "(" <<  c.x << ", " << c.y << ", " << c.z << ")";
    return out;
}

To copy to clipboard, switch view to plain text mode 

What is wrong / am I not getting?

Thanks!