C/C++ program to print the ellipse by mid point method

//program to print the ellipse by mid point method

Source code

#include<dos.h>

#include<math.h>

#include <graphics.h>

#include <stdlib.h>

#include <stdio.h>

#include <conio.h>

void plotellipse(int x,int y)

{

int xmax=getmaxx();

int ymax=getmaxy();

putpixel(x+xmax/2,ymax/2-y,15);

putpixel(x+xmax/2,ymax/2+y,15);

putpixel(xmax/2-x,ymax/2-y,15);

putpixel(xmax/2-x,ymax/2+y,15);

}

int main(void)

{

  /* request auto detection */

  int gdriver = DETECT, gmode, errorcode;

  int xmax, ymax,x,y;

  float d;

  int a,b,i;

  printf("Enter the value a&b ");

  scanf("%d%d",&a,&b);

  clrscr();

  /* initialize graphics and local variables */

  initgraph(&gdriver, &gmode, "");

  /* read result of initialization */

  errorcode = graphresult();

  /* an error occurred */

  if (errorcode != grOk)

  {

     printf("Graphics error: %s\n", grapherrormsg(errorcode));

     printf("Press any key to halt:");

     getch();

     exit(1);

  }

  setcolor(getmaxcolor());

  xmax = getmaxx();

  ymax = getmaxy();

  x=xmax/2;

  y=ymax/2;

  d=pow(b,2)-pow(a,2)*b+pow(a,2)/4;

  for(i=0;i<xmax;i++)

   putpixel(i,y,15);

  for(i=0;i<ymax;i++)

   putpixel(x,i,15);

  x=0;

  y=b;

  while((pow(a,2)*(y-.5))>(pow(b,2)*(x+1)))

    {

     if(d<0)

      {

d+=(pow(b,2)*(2*x+3));

x++;

      }

     else

      {

d+=pow(b,2)*(2*x+3)+pow(a,2)*(-2*y+2);

x++;

y--;

      }

     plotellipse(x,y);

     delay(10);

    }

  d=pow(b,2)*pow((x+.5),2)+pow(a,2)*pow((y-1),2)-pow(a,2)*pow(b,2);

  while(y>0)

    {

     if(d<0)

      {

d+=pow(b,2)*(2*x+2)+pow(a,2)*(-2*y+3);

x++;

y--;

      }

     else

      {

d+=pow(a,2)*(-2*y+3);

y--;

      }

     plotellipse(x,y);

     delay(100);

    }

  /* clean up */

  getch();

  closegraph();

  return 0;}