Bresenham's line drawing algorithm in Graphics

#include<graphics.h>

#include<stdio.h>

#include<conio.h>

#include<math.h>

void Bresenham(int,int,int,int);

int x1,y1,x2,y2;

void main()

{

  int gd = DETECT,gm;

  initgraph(&gd,&gm,"C:\\TC\\BGI");

  printf("Enter x1, y1, x2, y2: ");

  scanf("%d%d%d%d",&x1,&y1,&x2,&y2);

  Bresenham(x1,y1,x2,y2);

  getch();

  closegraph();

}

void Bresenham (int x1,int y1,int x2,int y2)

{

  int x,y,dx,dy,pk,k,xEnd;

  dx=abs(x2-x1);

  dy=abs(y2-y1);

  

  if(x1<x2)

  {

    x = x1;

    y = y1;

    xEnd = x2;

  }

  else

  {

    x = x2;

    y = y2;

    xEnd = x1;

  }

  

  putpixel (x,y,1);

  pk=2*dy-dx;

  

  while (x<=xEnd)

  {

    if(pk<0)

    {

      x=x+1;

      y=y;

      pk=pk+2*dy;

    }

    else

    {

      x=x+1;

      y=y+1;

      pk = pk+2*dy-2*dx;

    }

  

    putpixel (x,y,1);

  }

}

OUTPUT:

Circle Drawing Algorithm in CG >>