C++, 클래스 선언 외부에 클래스 생성자의 정의를 넣을 수없는 이유는 무엇입니까?

Question

클래스 선언 외부에 parameters-initialize리스트가있는 클래스 생성자의 정의를 넣을 수없는 이유는 무엇입니까?

typedef unsigned int UINT; 

class num_sequence { 
public: 
    typedef vector<UINT>::iterator iterator; 

    //I cannot put this following part in the cpp file 
    num_sequence(vector<UINT> & ele,int len=0,int beg=0):_relems(ele),_length(len),_beg_pos(beg) 
    { 
     //an abstract class cannot be instanlized 
     cout<<"build a num_sequence object"; 
    }  
    virtual ~num_sequence(); 

Answer 1

num_sequence.h

#include <vector> 

typedef unsigned int UINT; 

class num_sequence 
{ 
public: 
    typedef std::vector<UINT>::iterator iterator; 

    num_sequence(std::vector<UINT> & ele, int len = 0, int beg = 0); 
    virtual ~num_sequence(); 

private: 
    std::vector<UINT> &_relems; 
    int _length; 
    int _beg_pos; 
}; 

num_sequence.cpp

#include "num_sequence.h" 
#include <iostream> 

num_sequence::num_sequence(std::vector<UINT> & ele, int len, int beg) 
    : _relems(ele), _length(len), _beg_pos(beg) 
{ 
    std::cout << "build a num_sequence object"; 
}  

num_sequence::~num_sequence() 
{ 
}