程序代码：

#include"graphics.h"
void MidpointLine(int x0,int y0,int x1,int y1,int color)
{
    int a,b,dalte1,dalte2,d,x,y;
    a=y0-y1;
    b=x1-x0;
    dalte1=a+a;
    dalte2=a+a+b+b;
    d=a+a+b;
    x=x0;
    y=y0;
    putpixel(x,y,color);
    while(x0<x1)
    {
        if(d<0)
        {
            x++;
            y++;
            d+=dalte2;
        }
        else
        {
            x++;
            d+=dalte1;
        }
      x0++;
      putpixel(x,y,color);    /*改了这*/
      }
}
int main()
{
int graphdriver=DETECT;
int graphmode=0;
initgraph(&graphdriver,&graphmode,"d:\\win-tc\\projects");    /*换回自己模板*/
MidpointLine(10,20,400,300,2);
getch();
closegraph();
return 0;
}