Bezier Curve in C++ Graphics

Bezier Curve

#include<graphics.h>
#include<conio.h>
#include<math.h>

#define address "d:\\tc\\bgi"

struct Point{
    double x,y;
}c[]={{100,100},{105,140},{140,105},{150,115}};
int n=3;

void draw_Bezier(struct Point[]);
Point getPU(double);
double com(int,int);
double b(int,int,double);
void main()
{
    int sel=0;
    int gd=DETECT,gm,x,y;
    initgraph(&gd,&gm,address);
ABOVE:
    cleardevice();
    draw_Bezier(c);
    char ch=getch();
    if(ch==27) return;
    sel=ch-'0';
    if(sel<0||sel>3) sel=3;
    c[sel].x=c[sel].x+1,c[sel].y=c[sel].y+1;
    goto ABOVE;
}

void draw_Bezier(struct Point c[]){
    Point Pu,oPu;
    oPu.x=c[0].x,oPu.y=c[0].y;
    setcolor(WHITE);
    for(double u=0.1;u<=1.0;u+=0.1)
    {
           Pu=getPU(u);
           line(oPu.x,oPu.y,Pu.x,Pu.y);
           oPu=Pu;
    }
    setcolor(RED);
    for(int i=0;i<=n;i++)
    {
        circle(c[i].x,c[i].y,2);
        if(i>0) line(c[i-1].x,c[i-1].y,c[i].x,c[i].y);
    }

}
Point getPU(double u){
    Point p={0,0};
    for(int i=0;i<=n;i++)
    {
        p.x=p.x+c[i].x*b(n,i,u);
        p.y=p.y+c[i].y*b(n,i,u);
    }
    return p;
}

double b(int n,int k,double u)
{
       return com(n,k)*pow(u,k)*pow(1-u,n-k);
}
double com(int n,int k)
{
    double result=1;
    for(int i=n;i>n-k;i--)
    {
        result=(result*i)/(n-i+1);
    }
    return result;
}