yong.cpp

圆的实现

#include <iostream>
#include <cmath>
using namespace std;

class sjiao  
{
public:
	void zchang();
	void mji();
	bool pduan();
	sjiao();
	virtual ~sjiao();

private:
	double C;
	double e3;
	double e2;
	double e1;
	double y3;
	double y2;
	double y1;
	double x3;
	double x2;
	double x1;
};



sjiao::sjiao()
{
    x1=0;y1=0;
	x2=0;y2=0;
	x3=0;y3=0;
}

sjiao::~sjiao()
{
     cout<<"the work is finish."<<endl;
}



bool sjiao::pduan()
{
   cout<<"请输入坐标:"<<endl;
   cin>>x1>>y1>>x2>>y2>>x3>>y3;

   e1=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
   e2=sqrt((x1-x3)*(x1-x3)+(y1-y3)*(y1-y3));
   e3=sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
   
                    //判断是否为三角形
	if(e1+e2<=e3||e1+e3<=e2||e3+e2<=e1) 
		return false;

	 else 
		 return true;
}

void sjiao::zchang()
{
    C=e1+e2+e3;
	cout<<"周长为:"<<C<<endl;
}

void sjiao::mji()
{   double S;
   S=sqrt(C/2*(C/2-e1)*(C/2-e2)*(C/2-e3));
   cout<<"面积为:"<<S<<endl;

}


int main()
{
	sjiao G;
	if(G.pduan())
	{
		G.zchang();
		G.mji();
	}
	else
		cout<<"错误!"<<endl;
	

	return 0;
}