So ang will be an angle in radians from -PI to +PI, and you want to get a number between, say, 0 and 12, right?

First of all, you need to make ang be positive.  So add PI.  It will now be between 0 and TWOPI.

Next, you need to scale ang to be between 0.0 and 1.0.  So divide by TWOPI.

Finally you need to make ang be between 0.0 and 12.0, so multiply by 12.

Finally, if you're just dealing with the hour hand, you would want ang to be an whole number (throw away the fraction part) so you would either call floor or convert to an int.

Hope that's clear, and from that you can write some code

oops!

This ends up doing the job but there's a problem with the segmentation. What happens is when you get pt/TWO_PI = 1.0 is an unequal division. something like 000000,1111111,222222,3,000000,111111
                                                                |
                                                                | ... How can I even this out??

Code:

  float pt = ang+PI;
  pt=pt/TWO_PI;
  pt=pt*4;
  int pt1=floor(pt);