why is a const array not accessible from a constexpr function?

Question

i have a constexpr function named access, and i want to access one element from an array:

char const*const foo=\"foo\";
char const*const bar[10]={\"bar\"};

con         


        

Answer 1

The array needs to be declared constexpr, not just const.

constexpr char const* bar[10]={"bar"};

Without that, the expression bar[0] performs an lvalue-to-rvalue conversion in order to dereference the array. This disqualifies it from being a constant expression, unless the array is constexpr, according to C++11 5.19/2, ninth bullet:

an lvalue-to-rvalue conversion unless it is applied to

• a glvalue of literal type that refers to a non-volatile object defined with constexpr

(and a couple of other exceptions which don't apply here).