在mac上试了一下，很简单的Complex类的代码无法跑动，请问是什么原因？如何解决？
main.cpp

#include <iostream>
#include "Complex1.h"
using namespace std;

int main() {

    Complex1 a(2.0, 3.0);
    
    return 0;
}

Complex1.h

#include <iostream>
using namespace std;

class Complex1{

public:
    Complex1();
    Complex1(double r, double i);
    virtual ~Complex1();

private:
    double _r;
    double _i;
};

Complex1.cpp

#include <iostream>
#include "Complex1.h"
using namespace std;


Complex1::Complex1() {
	_r = 0.0;
	_i = 0.0;
	//cout << "Complex::Complex()" << endl;
}

Complex1::Complex1(double r, double i) {
	_r = r;
	_i = i;
	//cout << "Complex::Complex(double r, double i)" << endl;
}

Complex1::~Complex1() {
	_r = _i = 0.0;
	//cout << "Complex::~Complex()" << endl;
}

报错这样显示