实验3

#include<iostream>
using namespace std;
class rectangle{
    public:
        void setlw(int newL=0,int newW=0);
        void showarea();
    private:
        int length,width,area;
};//定义矩形类
void rectangle::setlw(int newL,int newW){
    length=newL;
    width=newW;
    area=length*width;
}
inline void rectangle::showarea(){
    cout<<"矩形的面积为："<<area<<endl;
}
int main(){
    rectangle myrectangle;
    cout<<"请输入长，宽："<<endl;
    int l,w;
    cin>>l>>w;
    myrectangle.setlw(l,w);
    myrectangle.showarea();
    return 0; 
}

#include<iostream>
using namespace std;
class Complex{
    public:
        Complex(double a,double b);
        Complex(double a);
        void add(Complex &c);
        void show();
    private:
        double real,imaginary;    
};
void Complex::add(Complex &c){
    real+=c.real;
    imaginary+=c.imaginary;
}
void Complex::show(){
    cout<<real<<(imaginary>0?'+':'-')<<imaginary<<"i"<<endl;
}
Complex::Complex(double a,double b){
    real=a;
    imaginary=b;
}
Complex::Complex(double a){
    real=a;
    imaginary=0;
}
int main(){
    Complex c1(3,5);
    Complex c2=4.5;
    c1.add(c2);
    c1.show();
    return 0;
}

通过对类的学习，能够将简单的现实世界中的对象以函数形式反映出来。