Difference between `constexpr` and `const`

Question

What\'s the difference between constexpr and const?

• When can I use only one of them?
• When can I use both and how should I

Answer 1

const applies for variables, and prevents them from being modified in your code.

constexpr tells the compiler that this expression results in a compile time constant value, so it can be used in places like array lengths, assigning to const variables, etc. The link given by Oli has a lot of excellent examples.

Basically they are 2 different concepts altogether, and can (and should) be used together.