Hi all,
I have to make a graphics project about drawing a circle like:
1/Draw the circle on the screen with yellow pen color and dark blue background. (Note: yellow
color: 0xFFFF00, dark blue color: 0x191970).
2/ Rotate the circle counterclockwise around the center I with the speed 10 degree per second, the
rotating will stop when user press ‘q’.
but I just did the first requirement.
Here is my work, can you help me with the second requirement!

Here is my work, can you help me with the second requirement!

Sure we can help you, but that's such a vague question ...
Where are you having problems with ?

Hmmm seems like you need to bust out the math book. I honestly dont remember the math functions in CMath, but you should probably look it up. I also don't know how the library you are using supports key entry for stopping, so I'll just say its called GetKey() and returns a character. Also I don't know anything about your circle class, but I will assume it accepts 2 coordinates and a radius.

double fX = 0;
double fY = 0;
double fAngle = 0;  //in radians
const int ciRadius = 10;
const double cfPi = 3.14159;
const int ciAngularVelocity = 10;  //in degrees
const int ciAmplitude = 100;
while (GetKey() != 'q')
    fX = SIN(fAngle) * ciAmplitude;
    fY = COS(fAngle) * ciAmplitude;
    DrawCircle(iX, iY, ciRadius)
    sleep(1000); //pause for a second
    fAngle += (ciAngularVelocity * (cfPi / 180.0f));

Something like that should do the trick. Probably not the exact code you need for your specific application, but it should give you a damn good idea.