When implementing operator[] how should I include bounds checking?

Question

First of all I apologize for the long lead up to such a simplistic question.

I am implementing a class which serves as a very long 1 dimensional index on a space fil

Answer 1

Having an operator[] that never fails sounds nice, but may hide bugs later on, if a calling function uses an illegal offset, finds a value from the beginning of the buffer, and proceeds as if that is a valid value.