Anyone knows how to fix compile error: LNK2005? (Source Code inside)

using namespace std;

typedef struct {
    DWORD	address;
    DWORD	size;
    char	file[64];
    DWORD	line;
} ALLOC_INFO;

typedef list<ALLOC_INFO*> AllocList;
//AllocList *allocList;

extern AllocList *allocList;

AllocList *allocList;

inline void * __cdecl operator new(
    unsigned int size,
    const char *file,
    int line);

extern AllocList *allocList;