c++ - What does does a dynamic memory request cause error? -

class tower { public:     unsigned int no;             // error!     int *levels = new int[no];   // error disappears when comment out line     tower(int init) {no = init;}     }; 

i made class declaration show above, , reason, doesn't work. error message shows is: invalid use of non-static data member 'tower::no'. why? i'm not sure going on.

can help?

thanks!

in tower.h :

class tower  { public:     tower(int size);  // note we're missing destructor                        // should invoke delete[] on _levels.     unsigned int _size;     int *_levels;  // consider sort of smart pointer                     // later when continue learn c++,                     // or use std::vector! }; 

in tower.cpp :

tower::tower(int size) : _size(size), _levels(null) {     if(_size > 0)     {         _levels = new int[size];     } } 

check out examples online too.