重载遇到的问题

complex.h的

#if ! defined(COMPLEX_H_)

#define COMPLEX_H_



class complex

{

///Attributes:

private:

    double real;

    double image;

    double radius;

    double angle;

///Operations:

public:

    complex(double real = 0, double image = 0);

    complex(const complex &c);

    ~complex(){};

    void setvalue(double real, double image);

    double getreal(){return real;}

    double getimage(){return image;}

    double getradius(){return radius;}

    double getangle(){return angle;}

    complex operator +(complex comp);

    complex operator *(complex comp);

    complex operator !();

    operator double();

};





#endif

complex.cpp

#include "complex.h"

#include <iostream>

#include <cmath>

using std::cout;

using std::endl;



complex::complex(double real, double image)

{

    cout << "Construct Function!" << endl;

    setvalue(real, image);

}



complex::complex(const complex &c)

{

    cout << "Copy Construct Function!" << endl;

    setvalue(c.real, c.image);

}



void complex::setvalue(double real, double image)

{

    this->real = real;

    this->image = image;

    this->radius = sqrt(real * real + image * image);

    this->angle = atan2(image, real);

}



complex complex::operator +(complex comp)

{

    cout << "+ override function" << endl;

    return complex(this->real + comp.real, this->image + comp.image);

}

complex complex::operator *(complex comp)

{

    ///(a+bi)(c+di) = ac + (ad+bc)i - bd = ac - bd + (ad+bc)i

    return complex(this->real * comp.real - this->image * comp.image,

                   this->real * comp.image + this->image * comp.real);

}

///重载！求复数的共轭复数

complex complex::operator !()

{

    return complex(this->real, -this->image);

}

///重载double()求复数的模

complex::operator double()

{

    return fabs(radius);

}

main.cpp

#include <iostream>

#include "complex.h"

using std::cin;

using std::cout;

using std::endl;



int main(void )

{

    double real1,image1,real2,image2;



    cout << "Please the first complex:" << endl;

    cin >> real1 >> image1;

    cout << "Please the second complex:" << endl;

    cin >> real2 >> image2;

    complex comp1(real1, image1);

    complex comp2(real2, image2);

    cout << (comp1+comp2).getreal() << endl;

    return 0;

}

不用看完整的类定义，只需要看下重载的+那个函数定义即可，我在main中只用了+做试验，但是用了之后，发现在gcc（code::blocks）下输出这种结果

Please the first complex:

1.1 2.2

Please the second complex:

3.3 4.4

Construct Function!

Construct Function!

Copy Construct Function!

+ override function

Construct Function!

4.4

我明白最后出现Construct Function!是用了RVO(Return Value Optimization)，但是在调用重载+函数之前为何会有一个Copy Construct Function!
这是什么原因呢？它拷贝构造的谁呢？
还有一个问题，那就是拷贝构造函数如果在参数中不加const，运行结果会不对，原因是重载了double，但是我在拷贝构造函数里面也没有改变参数的值，为何会有区别呢？

以上两个问题，已困扰多日，希大侠帮忙解决下，谢谢了。