On an 80x25 display, you could start with
char display[25][80];
Fill it with spaces.
Use the parametric form of
x = cx + r * cos(theta)
y = cy + r * sin(theta)
You don't need many angles to get a complete circle on such a small display.
When you're done, just loop and print the array.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Well, if I'm not mistaken, in my assignment on drawing circle a few yeras ago, you just need to draw a quarter of the circle's region. The other regions can be mirrored by the x=0, y=0 and x=y.
