#include <graphics.h>
void circle(int x, int y, int radius);
 

circle draws a circle in the current drawing color with its center at
(x,y) and the radius given by radius.
The linestyle parameter does not affect arcs, circles, ellipses, or pie
slices. Only the thickness parameter is used.
If your circles are not perfectly round, adjust the aspect ratio.

/* circle example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int midx, midy, radius = 100;
 
   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, "");
 
   /* read result of initialization */
   errorcode = graphresult();
   if (errorcode != grOk) {   /* an error occurred */
printf("Graphics error: %s\n", grapherrormsg(errorcode));
 
printf("Press any key to halt:");
getch();
exit(1);   /* terminate with an error code */
   }
 
   midx = getmaxx() / 2;
   midy = getmaxy() / 2;
   setcolor(getmaxcolor());
 
   /* draw the circle */
   circle(midx, midy, radius);
   /* clean up */
   getch();
   closegraph();
   return 0;
}

arc ellipse fillellipse getaspectratio sector setaspectratio

  no output of example at the moment
  do not hesitate and add it...