C默认构造函数

main.cpp: In function aint main()a:
main.cpp:38: error: no matching function for call to aComplex::Complex(Complex)a
main.cpp:22: note: candidates are: Complex::Complex(Complex&)
main.cpp:15: note:                 Complex::Complex(double,double)

但是当我将复制构造函数的参数类型更改为const Complex&时,它可以工作.
我认为默认构造函数将使用2 Complex :: Complex(2.0,0.0)调用,然后将调用复制构造函数来创建一个带有Complex(2.0.0)的副本.不正确吗？

#include <iostream>
using namespace std;

class Complex {
        double re;
        double im;

public:
        Complex(double re=0,double im=0);
        Complex(Complex& c);
        ~Complex() {};
        void print();
};

Complex::Complex(double re,double im)
{
        cout << "Constructor called with " << re << " " << im << endl;
        this->re = re;
        this->im = im;
}

Complex::Complex(Complex &c)
{
        cout << "Copy constructor called " << endl;
        re = c.re;
        im = c.im;
}


void Complex::print()
{
        cout << "real = " << re << endl;
        cout << "imaginary = " << im << endl;
}

int main()
{
        Complex a = 2;
        a.print();
        Complex b = a;
        b.print();
}