C++编译时出错

用的是Dev-C++

#include <iostream>
using namespace std;
class Point
{
public:
Point(float x=0,float y=0);
void setPoint(float,float);
float getX() const {return x;}
float getY() const {return y;}
friend ostream& operator < <(ostream&,const Point&);
protected:
float x,y;
};
class Circle:public Point
{
public:
Circle(float x=0,float y=0,float r=0);
void setRadius(float);
float getRadius() const;
float area() const;
friend ostream& operator < <(ostream&,const Circle&);
private:
float radius;
};

Point::Point(float a,float b)
{x=a;y=b;}

void Point::setPoint(float a,float b)
{x=a;y=b;}

Circle::Circle(float a,float b,float r):Point(a,b),radius(r){}

void Circle::setRadius(float r)
{radius=r;}
float Circle:

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