c++ - How I can auto increment each class objects? -

i have class contain 2 private int , 1 const (m_id) , other 1 static (next_id).

i want set m_id next_id , increment next_id each time create object of class.

but since it's const can't set :

class::class()  { m_id = next_id++; } 

i need set

class::class() :m_id(next_id) { next_id++; } 

but that's not either because can't access private static that.

someone told me const not intented used that, remove it. solution?

edit : here full header , source

header

#ifndef entity_h_lea12oed #define entity_h_lea12oed  #include "entitykey.h" #include "componentmanager.h" class entity { public:     entity ();     virtual ~entity ();  private:     ekey m_key;      componentmanager m_componentmanager;     const int m_id;     static int next_id; };  #endif /* end of include guard: entity_h_lea12oed */ 

source

#include "entity.h"  entity::entity() :m_id(next_id++) {  }  entity::~entity() { }    

(of course entitykey , componentmanager doesn't have question)

(edit 2: corrected errors in code due testing)

you need define next_id, or else compile, but not link. so:

class class {     /* whatever */ };  class::class() :m_id(next_id++) {     /* whatever */ }  int class::next_id = 0;