c++ - Assigning to a static const member a value coming from a function (from a static method, to be more precise) -

the following not allowed ('std::numeric_limits::max()' cannot appear in constant-expression):

#include <limits>     struct mystruct {  private:     static const unsigned int invalid_value = std::numeric_limits<unsigned int>::max();  public:   unsigned int index;    inline mystruct() : index(invalid_value) {} }; 

which best way obtain desired behaviour? like, if possible, have invalid_value known @ compile time (e.g. allow compiler doing better optimization).

how define constant ~0u. since unsigned int defined "direct binary representation", inverse thereof should bits set.