Constant expressions in C++11

Lecture 6 - Slide 32 : 40

A constant expression - constexpr - can be evaluated at compile time, as well as run-time - a C++11 feature

In contrast, const means immutable - cannot be modified at run-time.

constexpr
- Expressive power:
  - Integers, floating-point, and enumeration values
  - Any operator that does not modify a program state
  - Literal types - structs, or classes with a consexpr constructor
  - constexpr functions - pure functions - (relaxed in C++14)
    - Single return
    - No loops, no local variables, no side-effects
    - Recursion
    - Conditional expressions can be used: - the operator ?: