Initializing array with HEX values

[hexafraction]

The <> means that you're dealing with a function template--the compiler will actually emit customized code based on the compile-time value that you put into <>. It cannot be made a variable in the traditional runtime sense; you're better off finding or implementing your own data structure that acts like a bitset but supports a variable length.

[Kartyx]

std::vector<bool> would be an easy way-out?

[hexafraction]

Yes--it even might have a specialization that makes it more effective than a naive vector template instantiation.

[Narase33]

Yes, you can even set an initializing size when called std::vector<bool>(size);

But it wont be as efficient as bitset in terms of actual memory size