Relation between constexpr and pure functions

Question

Am I right, that:

• Any function defined with constexpr is a pure function, and
• Any pure function can be and must be defined with con

Answer 1

In addition to the previous answers: constexpr on a function restricts its implementation greatly: its body must be visible to the compiler (inline), and must consist only of a single return statement. I'd be surprised if you could implement sqrt() or sin() correctly and still meet that last condition.