10-8.cpp

为初学者提供的最佳的C++程序设计源程序库

#include<iostream.h>
#include<iomanip.h>
class Line
{
private:
    	double x1,x2,y1,y2;
public:
    	Line(){ };
    	Line(double a,double b,double c,double d)
     	{
        		x1=a;y1=b;x2=c;y2=d;
        		cout<<"线段端点:"<<x1<<","<<y1<<")-("<<x2<<","\
        			<<y2<<")"<<endl;
      	};
   	friend twoline(Line l1,Line l2)   //友元函数
   	{
     		double r1=l2.y1*(l2.x2-l1.x1)-l1.y1*(l2.x2-l2.x1)+(l1.x1-l2.x1)*(l2.y2-l2.y1);
     		double r2=(l1.y2-l1.y1)*(l2.x2-l2.x1)-(l1.x2-l1.x1)*(l2.y2-l2.y1);
     		double  r=r1/r2;
     		double t=((l1.x1-l2.x1)+r*(l1.x2-l1.x1))/(l2.x2-l2.x1);
     		if(r>0&&r<1&&t>0&&t<1)
       			cout<<"两线段相交."<<endl;
     		else if(r>0&&r<1&&t>=1)
       			cout<<"两线段不相交,一条在另一条的一侧."<<endl;  
     		else if((r>=1||r<=0)&&t>0&&t<1)
       			cout<<"两线段不相交,一条在另一条的一侧."<<endl;  
     		else 
       			cout<<"两线段不相交."<<endl;
   	}
};
void main()
{
  	Line A(2,2,18,18),B(1,12,19,5);
  	twoline(A,B);
}