There are const variables that arean't constant expressions; there are also constant expressions that don't have an overt const qualifier. Confused? Knowing the rules will help you avoid common mishaps.
onstant expressions are tricky. Not all of them have an overt const qualifier. Furthermore, in some cases, a const-qualified variable is just a constant, but not a constant expression. These nuances aren't just bits of C++ trivia. Rather, they affect the correctness of your code and its performance. The following sections explain the rules of constant integral expressions and show how to avert common mishaps.
How do you know whether an expression is a constant expression? How do you turn a non-constant expression into a constant expression when necessary?
onstant expressions are tricky. Not all of them have an overt 
