vc2008如何输入多点坐标来实现多边形面积的计算？

Question

题目如图。求大神解答，尽可能详细点，谢谢

Answer 1

本质上讲,这是一个数学问题

deftype struct point
{
    double x;
    double y;
};
double get_Area_4(point A,point B,point C,point D)
{
    double x_=(A.x+B.x+C.x+D.x)/4;
    double y_=(A.y+B.y+C.y+D.y)/4;
    return ( 
                (A.x+x_)*(A.y-y_)+
                (B.x+x_)*(B.y-y_)+
                (C.x+x_)*(C.y-y_)+
                (D.x+x_)*(D.y-y_) 
            )/2;
}
main()
{
    printf("请输入4个点坐标,X1,Y1,X2,Y2...");
    point a,b,c,d;
    scanf("%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf"
    ,a.x,a.y,b.x,b.y,c.x,c.y,d.x,d.y);
    printf("四边形的面积是%lf",get_Area_4(a,b,c,d));
}