谁帮我看看这个bresenham直线算法程序不能运行

我写了一个bresenham直线算法程序,是多点的,但是输入端点坐标后没有结果,请哪位高手指教?



#include<graphics.h>
#include<stdlib.h>
#include<stdio.h>
#include<conio.h>
#include<dos.h>
int main(void)
{
int gdriver=DETECT,gmode;
int sx;
int sy;
int i;
int x1;
int y1;
int x2;
int y2;
int dx;
int dy;
int t1;
int t2;
int g;
initgraph(&gdriver,&gmode,"C:\\tc");

printf("please input points of the line:\n");
scanf("%d,%d,%d,%d\n",&x1,&y1,&x2,&y2);
dx=fabs(x2-x1);
dy=fabs(y2-y1);
t1=2*dy;
t2=2*(dy-dx);
g=2*dy-dx;
if(x2<x1)
sx=-1;
else
sx=1;
if(y2<y1)
sy=-1;
else
sy=1;
 setbkcolor(0);
 cleardevice();

if(dx>dy)
{
  if(dx>2*dy)
    {
      for(i=1;i<=(dx-dy);i++)
       {
        
        x1+=sx;
        if(g<0)
        {g+=t1;}
        else
        {y1+=sy;
        putpixel(x1,y1,100);
        x1+=sx;
        g+=(t1+t2);}
       }
    putpixel(x1,y1,100);
}
  else
    {
      for(i=1;i<=dy;i++)
       {
        putpixel(x1,y1,100);
        x1+=sx;
        if(g<0)
        {putpixel(x1,y1,100);
        x1+=sx;
        y1+=sy;
        g+=(t1+t2);}
        else
        {y1+=sy;
        g+=t2;}
       }
    }
}
else
{
   g=2*dx-dy;
   t1=2*dx;
   t2=2*dx-2*dy;
  if(dy<2*dx)
    {
      for(i=1;i<=dx;i++)
       {
        putpixel(x1,y1,100);
        y1+=sy;
        if(g<0)
        {putpixel(x1,y1,100);
        x1+=sx;
        g+=(t1+t2);}
        else
        {x1+=sx;
        y1+=sy;
        g+=t2;}
       }
    }
  else
    {
      for(i=1;i<=(dy-dx);i++)
       {
        putpixel(x1,y1,100);
        y1+=sy;
        if(g<0)
        {g+=t1;}
        else
        {x1+=sx;
        putpixel(x1,y1,100);
        y1+=sy;
        g+=(t1+t2);}
       }
    }
}
           
getch();
closegraph();
return 0;
}