以点类为基类,定义矩形类和圆类.矩形由左下方的顶点和长宽定义.圆由圆心和半径定义.

class point
{
int x;
int y;
}

class rectangle
{
point lb_point; //左下方的顶点
int length;
int height;
}

class circle
{
point center;
int r;
}

举例判断是在圆里面还是外面
int judge(point pt,circle cl)
{
int pt_x,pt_y,c_x,c_y;
double distance;
pt_x = pt.x;
pt_y = pt.y;
c_x = c.center.x;
c_y = c.center.y;
distance = (pt_x - c_x)*(pt_x - c_x) + (pt_y - c_y)*(pt_y - c_y);
if(r*r = distance)
return 0; //图形上
else (r*r > distance)
return -1; //图形里
else (r*r < distance)
return 1; //图形外

}

判断矩形也是类似的，判断点和矩形左下方顶点之间在X轴和Y轴上的距离跟矩形长和宽之间的关系