```
# include<stdio.h>
# include<graphics.h>
# include<math.h>
using namespace std;
int main(void)
{
int gd=DETECT,gm;
int r,x,y,p,xc=320,yc=240;
initgraph(&gd,&gm,NULL);
cleardevice();
printf("Enter the radius ");
scanf("%d",&r);
x=0;
y=r;
putpixel(xc+x,yc-y,1);
p=3-(2*r);
for(x=0;x<=y;x++)
{
if (p<0)
{
y=y;
p=(p+(4*x)+6);
}
else
{
y=y-1;
p=p+((4*(x-y)+10));
}
putpixel(xc+x,yc-y,1);
putpixel(xc-x,yc-y,2);
putpixel(xc+x,yc+y,3);
putpixel(xc-x,yc+y,4);
putpixel(xc+y,yc-x,5);
putpixel(xc-y,yc-x,6);
putpixel(xc+y,yc+x,7);
putpixel(xc-y,yc+x,8);
}
getch();
closegraph();
}
```

- installed graphics.h
- compiled using
`gcc filename.cpp -0 filename -lgraph`

- then used
`./filename`

- the window apperared for 10 seconds and the error below appears:

[xcb] Unknown sequence number while processing queue [xcb] Most likely this is a multi-threaded client and XInitThreads has not been called [xcb] Aborting, sorry about that. heart: ../../src/xcb_io.c:273: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed. Aborted

Any solutions?

`XInitThreads();`

as the first code at main()? – Aquarius Power May 27 at 8:23