Implementing non member functions
<p>I am working on an assignment and have hit a wall on a particular area.  I can't figure out how I am supposed to implement the non member functions from the header into the .cpp file.  Here is the header:</p>

<pre><code>class complx
{
    double real, imag;
public:
    complx( double real = 0., double imag = 0.); // constructor
    complx operator+(complx);       // operator+()

    complx operator+(double);       // operator+()with double
    complx operator- (complx);       // operator-()
    complx operator* (complx);       // operator*()

    bool operator== (complx);   // operator==()


    //Sets private data members.
    void Set(double new_real, double new_imaginary) {
        real = new_real;
        imag = new_imaginary;
    }

    //Returns the real part of the complex number.
    double Real() {
        return real;
    }

    //Returns the imaginary part of the complex number.
    double Imaginary() {
        return imag;
    }
};

ostream &amp;operator &lt;&lt; ( ostream &amp;out_file, complx number );

extern istream &amp;operator &gt;&gt; ( istream &amp;in_file, complx &amp;number );

extern ifstream &amp;operator &gt;&gt; ( ifstream &amp;in_file, complx &amp;number );

complx &amp;operator + (double, complx);
complx &amp;operator - (double, complx);
complx &amp;operator * (double, complx);
}
</code></pre>

<p>I have most of the member functions figured out, but it's the three at the bottom of the header that are giving me fits.  Any help would be greatly appreciated.  Thanks!</p>

<p>p.s. sorry for the formatting, it's not copying over very well.</p>
