c++程序设计实验3

类与对象

类相当于一个模板，而对象就是依据类这个模板打造出来的可以使用的工具。类是对象的抽象，对象是类的具体化。

构造函数与析构函数

• 构造函数用来初始化一个对象，构造和默认构造两种。
• 构造函数与析构函数的调用对等

矩形

#include<iostream>
using namespace std;
class Rectangle{
	double length,width;
	public :
		Rectangle();
		Rectangle(double l,double w);
		Rectangle(const	Rectangle &);
		~Rectangle();
		double getArea();
		void setData(double ,double);
};
Rectangle::Rectangle(double l,double w):length(l),width(w){
	cout<<"构造一个Rectangle对象"<<endl;
}
Rectangle::Rectangle():Rectangle(1.0,2.0){
}
Rectangle::Rectangle(const Rectangle &r)
{
	length=r.length;
	width=r.width;
	cout<<"复制构造一个Rectangle对象"<<endl; 
} 
Rectangle::~Rectangle()
{
	cout<<"析构一个Rectangle对象"<<endl;
}
double Rectangle::getArea()
{
	return length*width;
}
void Rectangle::setData(double l,double w)
{
	length=l;
	width=w;
}
int main()
{
	Rectangle r1;
	Rectangle r2(5.0,6.0);
	cout<<"r1的面积是："<<r1.getArea()<<endl;
	cout<<"r2的面积是："<<r2.getArea()<<endl;
	cout<<"重新设置r1的长和宽。"<<endl;
	double l,w;
	cin>>l>>w;
	r1.setData(l,w);
	cout<<"修改后r1的面积为："<<r1.getArea()<<endl;
	return 0;
 }  

Complex

#include<iostream>
using namespace std;
class Complex{
	double real,imaginary;
	public :
		Complex(double r,double i);
		Complex(double r);
		Complex();
		Complex(const Complex &c);
		~Complex();
		void set(double r,double i);
		void add(const Complex &c);
		void show();
};
Complex::Complex(double r,double i):real(r),imaginary(i){
	cout<<"构造一个Complex对象"<<endl; 
}
Complex::Complex(double r):real(r),imaginary(0){
	cout<<"构造一个Complex对象"<<endl;
}
Complex::Complex():Complex(0,0){
}
Complex::Complex(const Complex &c)
{
	real=c.real;
	imaginary=c.imaginary;
	cout<<"复制构造一个Complex对象"<<endl;
}
Complex::~Complex()
{
	cout<<"析构一个Complex对象"<<endl;
}
void Complex::set(double r,double i)
{
	real=r;
	imaginary=i;
}
void Complex::add(const Complex &c)
{
	real+=c.real;
	imaginary+=c.imaginary;
}
void Complex::show()
{
	cout<<real<<"+"<<imaginary<<"i"<<endl;
}
int main()
{
	Complex c1(3.5,4.5);
	Complex c2;
	Complex c3=3;
	cout<<"c1: ";
	c1.show();
	cout<<"c2: ";
	c2.show();
	cout<<"c3: ";
	c3.show();
	c2.set(5.6,3.5);
	cout<<"new c2: ";
	c2.show();
	c1.add(c3);
	cout<<"c1+c3=";
	c1.show();
	c3.add(c2);
	cout<<"c3+c2=";
	c3.show();
	return 0;
 }