Couple questions about millis()

Need a bit of clarity here: millis() is essentially a counter that starts running as soon as the program it's in begins to run correct? Can it be reset to zero and started again within the same sketch?
Mark

markba633csi:
Need a bit of clarity here: millis() is essentially a counter that starts running as soon as the program it's in begins to run correct?

Correct. Except that, unlike a simple counter, it may miss certain values.

Can it be reset to zero and started again within the same sketch?

Yes it can, but why would you want to?

Can it be reset to zero and started again within the same sketch?

About as easily, and sensibly, as setting your watch to noon at 2:30PM.

Could you elaborate on the "missing certain values"? Where is that documented?

millis usually increments by 1. It occasionally increments by 2. If your code is correct you will not care.

Or, you can use micros which increments by the same amount that varies by clock speed.