c++ - Singleton destructor called error -

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• what undefined reference/unresolved external symbol error , how fix it? 27 answers

#pragma once #include <time.h>          class ctimer {     time_t _last;     ctimer() { _last = time( null ); }     ctimer(const ctimer &);     ctimer& operator=(const ctimer&);     ~ctimer(); public:     static ctimer& getinstance(){                 static ctimer instance;         return instance;     }      float getdelta(){         time_t = time( null );         float delta = (float)(now - _last);              return delta;     }     //should called @ beginning of rendering function     void update(){         _last = time( null );     } }; 

this timer singleton code. wanted use that: somewhere in player class:

posx += vel * ctimer::getinstance().getdelta(); 

and in main loop file:

void gameloop(){ ctimer::getinstance().update(); ... } 

but error:

1>main.obj : error lnk2019: unresolved external symbol "private: __thiscall ctimer::~ctimer(void)" (??1ctimer@@aae@xz) referenced in function "void _cdecl public: static class getinstance & __cdecl ctimer::getinstance(void)'::2'::`dynamic atexit destructor 'instance''(void)" (??_finstance@?1??getinstance@ctimer@@saaav1@xz@yaxxz)

i think because main code tries call destructor, after loop ends , should change pointers singleton, maybe not. tell me how fix this?

if member of ctimer class time_t variable, don't need (not implemented, hence linking error) destructor, copy constructor , assignment operator. comment 3 lines: these functions generated compiler !