8-3(

C++多态性程序例子

#include <iostream.h>

class complex
{
public:
	complex() { real=imag=0; }
	complex(double r, double i)
	{
		real = r, imag = i;
	}
	friend complex operator +(const complex &c1, const complex &c2);
	friend complex operator -(const complex &c1, const complex &c2);
	friend complex operator *(const complex &c1, const complex &c2);
	friend complex operator /(const complex &c1, const complex &c2);
	friend 
		void print(const complex &c);
private:
	double real, imag;
};

complex operator +(const complex &c1, const complex &c2)
{
	return complex(c1.real + c2.real, c1.imag + c2.imag);
}

complex operator -(const complex &c1, const complex &c2)
{
	return complex(c1.real - c2.real, c1.imag - c2.imag);
}

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

complex operator /(const complex &c1, const complex &c2)
{
	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 print(const complex &c)
{
	if(c.imag<0)
		cout<<c.real<<c.imag<<'i';
	else
		cout<<c.real<<'+'<<c.imag<<'i';
}

void main()
{
	complex c1(2.0, 3.0), c2(4.0, -2.0), c3;
	c3 = c1 + c2;
	cout<<"\nc1+c2=";
	print(c3);
	c3 = c1 - c2;
	cout<<"\nc1-c2=";
	print(c3);
	c3 = c1 * c2;
	cout<<"\nc1*c2=";
	print(c3);
	c3 = c1 / c2;
	cout<<"\nc1/c2=";
	print(c3);
	c3 = (c1+c2) * (c1-c2) * c2/c1;
	cout<<"\n(c1+c2)*(c1-c2)*c2/c1=";
	print(c3);
	cout<<endl;
}