Moving Wheel

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

int l=1; 

void ddaline(int x1,int y1,int x2,int y2) 
{ 

 int s,dx,dy,m; 
 float xi,yi,x,y; 

 dx=x2-x1; 
 dy=y2-y1; 

 if(abs(dx)>abs(dy)) 
  s=abs(dx); 
 else 
  s=abs(dy); 

 xi=dx/(float)s; 
 yi=dy/(float)s; 

 x=x1; 
 y=y1; 

 putpixel(x1+0.5,y1+0.5,15); 

 for(m=0;m<s;m++) 
 { 
  x+=xi; 
  y+=yi; 
  putpixel(x+0.5,y+0.5,15); 
 } 
} 


void plotpoints1(int x,int y,int cx,int cy) 
{ 
 putpixel(cx+x,cy+y,15); 
 putpixel(cx-x,cy-y,15); 
 putpixel(cx-y,cy+x,15); 
 putpixel(cx+y,cy-x,15); 
 if(l%20==0) 
 { 
  ddaline(cx-x,cy-y,cx+x,cy+y); 
  ddaline(cx-y,cy+x,cx+y,cy-x); 
 } 
 l++; 
} 

void plotpoints2(int x,int y,int cx,int cy) 
{ 

 putpixel(cx-x,cy+y,15); 
 putpixel(cx+x,cy-y,15); 
 putpixel(cx+y,cy+x,15); 
 putpixel(cx-y,cy-x,15); 
 if(l%20==0) 
 { 
  ddaline(cx+x,cy-y,cx-x,cy+y); 
  ddaline(cx-y,cy-x,cx+y,cy+x); 
 } 
 l++; 
} 


void mcircle(int cx,int cy,int r) 
{ 
 int x=0,y,p; 

 y=r; 
 p=1-r; 


 while(x<y) 
 { 
  plotpoints1(x,y,cx,cy); 
  x++; 
  if(p<0) 
   p+=2*x+1; 
  else 
  { 
   y--; 
   p+=2*(x-y)+1; 
  } 
 } 



 x=y+1; 
 while(abs(x)>0) 
 { 
  plotpoints2(x,y,cx,cy); 
  x--; 
  if(p>=0) 
   p =p-2*x-1;
  else 
  { 
   y++; 
   p=p-2*(x-y)-1; 
  } 
 } 
} 

void main() 
{ 
 int gd=DETECT,gm=DETECT;
 int i=0;
 initgraph(&gd,&gm,"");

 while(!kbhit())
 {
  if(i>640) i = -200;
  cleardevice(); 
  mcircle(100+(i++),200,100); 
  delay(90);
  i++; 
 } 
 getch(); 
}
/******************************************************************/
/*                       WWW.CGLABPROGRAMS.COM                    */
/******************************************************************/

Hope, it helps! :)