复数的四则运算法则：

1. 加法：(a+bi)+(c+di)=(a+c)+(b+d)i
2. 减法：(a+b)-(c+di)=(a-c)+(b-d)i
3. 乘法：(a+bi)*(c+di)=(ac-bd)+(bc+ad)i
4. 除法：(a+bi)/(c+di)=((ac+bd)+(bc-ad)i)/(c2+d2)
   注意：在复数除法运算中，若c、d均为0，则不可计算（除数不能为0）。

1、代码中直接输入参数：
C++代码：

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;

class Complex {
public:
	Complex(double real, double imag) {
		this->real = real;
		this->imag = imag;
	}

	friend Complex operator+(Complex c1, Complex c2);
	friend Complex operator-(Complex c1, Complex c2);
	friend Complex operator*(Complex c1, Complex c2);
	friend Complex operator/(Complex c1, Complex c2);

	void Print_Complex();
private:
	double real;
	double imag;
};

Complex operator+(Complex c1, Complex c2) {
	return Complex(c1.real + c2.real, c1.imag + c2.imag);
}

Complex operator-(Complex c1, Complex c2) {
	return Complex(c1.real - c2.real, c1.imag - c2.imag);
}
 
Complex operator*(Complex c1, Complex c2) {
	return Complex(c1.real*c2.real - c1.imag*c2.imag, c1.real*c2.imag + c1.imag*c2.real);
}

Complex operator/(Complex c1, Complex c2) {
	if (c2.real == 0 && c2.imag == 0) {
		cout << "Error  ";
		return c2;
	}
	else {
		return Complex((c1.real*c2.real + c1.imag*c2.imag) / (c2.real*c2.real + c2.imag*c2.imag), (c1.imag*c2.real - c1.real*c2.imag) / (c2.real*c2.real + c2.imag*c2.imag));
	}
}

void Complex::Print_Complex() {
	if (real == 0) {
		cout << imag << "i" << endl;
	}
	else {
		if (imag > 0) {
			cout << real << "+" << imag << "i" << endl;
		}
		else {
			cout << real << imag << "i" << endl;
		}
		
	}
}

int main() {
	Complex c1(1, 3);
	Complex c2(1, 1);

	Complex c3 = c1 + c2;
	cout << "Add:";
	c3.Print_Complex();
	Complex c4 = c1 - c2;
	cout << "Minus:";
	c4.Print_Complex();
	Complex c5 = c1 * c2;
	cout << "Mul:";
	c5.Print_Complex();
	Complex c6 = c1 / c2;
	cout << "Div:";
	c6.Print_Complex();

	return 0;
}

C++运行结果：
说明：若c2的实部和虚部均为0，输出结果为：
2 、如果想自己输入参数，代码如下：
C++代码：

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;

class Complex {
public:
	Complex() {
		this->real = 0;
		this->imag = 0;
	}

	Complex(double real, double imag) {
		this->real = real;
		this->imag = imag;
	}

	void setRI(double real, double imag) {
		this->real = real;
		this->imag = imag;
	}

	friend Complex operator+(Complex c1, Complex c2);
	friend Complex operator-(Complex c1, Complex c2);
	friend Complex operator*(Complex c1, Complex c2);
	friend Complex operator/(Complex c1, Complex c2);

	void Print_Complex();
private:
	double real;
	double imag;
};

Complex operator+(Complex c1, Complex c2) {
	return Complex(c1.real + c2.real, c1.imag + c2.imag);
}

Complex operator-(Complex c1, Complex c2) {
	return Complex(c1.real - c2.real, c1.imag - c2.imag);
}
 
Complex operator*(Complex c1, Complex c2) {
	return Complex(c1.real*c2.real - c1.imag*c2.imag, c1.real*c2.imag + c1.imag*c2.real);
}

Complex operator/(Complex c1, Complex c2) {
	if (c2.real == 0 && c2.imag == 0) {
		cout << "c2 Error  ";
		return c2;
	}
	else {
		return Complex((c1.real*c2.real + c1.imag*c2.imag) / (c2.real*c2.real + c2.imag*c2.imag), (c1.imag*c2.real - c1.real*c2.imag) / (c2.real*c2.real + c2.imag*c2.imag));
	}
}

void Complex::Print_Complex() {
	if (real == 0) {
		cout << imag << "i" << endl;
	}
	else {
		if (imag > 0) {
			cout << real << "+" << imag << "i" << endl;
		}
		else {
			cout << real << imag << "i" << endl;
		}
		
	}
}

int main() {
	Complex c1, c2;

	double real, imag;
	cout << "Please input c1 real:";
	cin >> real;
	cout << "Please input c1 imag:";
	cin >> imag;
	c1.setRI(real, imag);

	cout << "Please input c2 real:";
	cin >> real;
	cout << "Please input c2 imag:";
	cin >> imag;
	c2.setRI(real, imag);

	Complex c3 = c1 + c2;
	cout << "Add:";
	c3.Print_Complex();
	Complex c4 = c1 - c2;
	cout << "Minus:";
	c4.Print_Complex();
	Complex c5 = c1 * c2;
	cout << "Mul:";
	c5.Print_Complex();
	Complex c6 = c1 / c2;
	cout << "Div:";
	c6.Print_Complex();

	return 0;
}

C++运行结果：