定义一个表示点的结构类型Point和一个由直线方程y = a

#include <iostream>
using namespace std;
struct point
{
   double x; double y;
};
class line
{
 public:
       line( double u, double v )
        {
 a=u;  b=v;  
}
       void print()
     {
 cout<<"y="<<a<<"x+"<<b<<endl;  
}
        friend point setpoint(line &l1,line &l2);
private:
        double a, b;
};
point setpoint( line &l1, line &l2 )
{
point p;
p.x=( l2.b-l1.b )/( l1.a-l2.a );
p.y=( l1.a*l2.b-l2.a*l1.b)/(l1.a-l2.a );
return p;
 }
int main()
{
 point setp;
      line l1(2,3), l2(4,5);
      cout<<"直线l1: ";
      l1.print();
      cout<<"直线l2: ";
      l2.print();
      setp=setpoint( l1,l2 );
      cout<<"直线l1和直线l2的交点:("<<setp.x<<","<<setp.y<<")"<<endl;
}