은 C++에서 연산자를 오버로드 할 수 없습니다

Question

저는 C++의 학습 과정에 있지만 자바 코드에서 C++ 로의 변환을 시도 할 때이 오류가 계속 발생합니다. C++ 코드 (C++ 스타일 프로그래밍 사용)로 변환해야하는 java 클래스가 있습니다. 나는 Article 클래스, Article로부터 상속받은 ArticleUnitaire 클래스, ArticleUnitaire로부터 상속받은 Ramette 클래스를 가진다. 모든 getters와 setter는 잘 작동하지만, 문제는 toString을 C++과 동등하게하려고 할 때입니다. 연산자는 < <입니다. 자바 코드 : 내가 당신에게 코드와 오류를 보여 드리죠 여기

public abstract class Article { 
     .... 
     public String toString() { 
     return this.getClass().getName() + ":reference=" 
      + reference + ";descriptif=" + getDescriptif() 
      + ";marque=" + getMarque() + ";PU=" + getPU(); 
     } 

    } 

public abstract class ArticleUnitaire extends Article { 
    private String marque; 
    private double pu; 
    private String descriptif; 

    public ArticleUnitaire(String reference) { 
    super(reference); 
    } 

    public ArticleUnitaire(String reference, String descriptif, String marque, 
         double pu) { 
    super(reference); 
    this.marque = marque; 
    this.pu = pu; 
    this.descriptif = descriptif; 
    } 



    // useless to redefine toString because PU and descriptif 
    // were also displayed by the superclass(Article) 

} 

public class Stylo extends ArticleUnitaire { 
.... 

    @Override 
    public String toString() { 
    return super.toString() + ";couleur=" + couleur; 
    } 
} 

내 articles.h 파일입니다

#include <string> 
    using namespace std; 



    class Article 
    { 
     public: 
     string getReference(); 
     virtual string getDescriptif() const; 
     virtual double getPU() const; 
     string getMarque() const; 
     void Afficher(ostream&) const; 
     ostream& operator<<(ostream&) const; 

     protected: 
     Article(string&); 
      string reference; 
     private: 

    }; 

    class ArticleUnitaire : public Article { 
     public: 
      ArticleUnitaire(string); 
      ArticleUnitaire(string, string, string, double); 
      string getMarque() const; 
      void setMarque(string&); 
      double getPU() const; 
      void setPU(double&); 
      void setDescriptif(string&); 
      string getDescriptif() const; 
      void Afficher(ostream&) const; 

     protected: 
      string marque; 
      double pu; 
      string descriptif; 
     private: 

    }; 

    class Stylo : public ArticleUnitaire { 
     public: 
      Stylo(string r, string d, string m, double p, string c); 
      void Afficher(ostream& os) const; 
      string getCouleur(); 
     protected: 
     private: 
      string couleur; 

    }; 

class Lot : public Article { 
    public: 
     Lot(string, Article, int, int); 
     double getPU() const; 
     string getDescriptif() const; 
     string getMarque() const; 
     int getNbArticles() const; 
     void setNbArticles(int&); 
     int getPourcentage() const; 
     void setPourcentage(int&); 
     Article getArticle() const; 
     void setArticle(Article&); 
     virtual void Afficher(ostream& os) const; 


    protected: 
    private: 
     int nb; 
     int pourcentage; 
     Article art; 
}; 

그리고 articles.cc 파일 : 그러나

#include <typeinfo> 
    #include <string> 
    using namespace std; 
    #include "articles.h" 

    /* Article */ 

    Article::Article(string& ref) : reference(ref) {}; 

    string Article::getReference() { 
     return reference; 
    } 

    ostream& Article::operator<<(ostream& os) const { 
     Afficher(os); 
     return os; 
    } 

    string Article::getMarque() const { 
     return "Sans marque"; 
    } 

    void Article::Afficher(ostream& os) const { 
     os << " : reference = " << getReference() << " ; descriptif = " << getDescriptif() << " ; marque = " << getMarque() << " ; PU = " << getPU(); 
    } 

    /* Article Unitaire */ 

    ArticleUnitaire::ArticleUnitaire(string r) : Article(r) {}; 

    ArticleUnitaire::ArticleUnitaire(string r, string d, string m, double p) : Article(r), marque(m), descriptif(d), pu(p) {}; 

    string ArticleUnitaire::getMarque() const { 
     return marque; 
    } 

    void ArticleUnitaire::setMarque(string& m) { 
     marque = m; 
    } 

    double ArticleUnitaire::getPU() const { 
     return pu; 
    } 

    void ArticleUnitaire::setPU(double& p) { 
     pu = p; 
    } 

    void ArticleUnitaire::setDescriptif(string& d) { 
     descriptif = d; 
    } 

    string ArticleUnitaire::getDescriptif() const { 
     return descriptif; 
    } 

    /* Stylo */ 

    Stylo::Stylo(string r, string d, string m, double p, string c) : ArticleUnitaire(r,d,m,p), couleur(c) {}; 

    string Stylo::getCouleur() { 
     return couleur; 
    } 

    void Stylo::Afficher(ostream& os) const { 
     Article::Afficher(os); 
     os << " ; couleur = " << getCouleur(); 
    } 

Lot::Lot(String r, Article a, int n, int p) : Article(r) { 
    art = a; 
    nb = n; 
    pourcentage = p; 
}; 
... 

컴파일을 시도 할 때 Afficher() 메서드에 대해 동일한 오류가 계속 발생합니다.

In member function ‘void Article::Afficher(std::ostream&) const’: 
articles.cc:24:9: error: no match for ‘operator<<’ in ‘os << " : reference = "’ 
articles.cc:24:9: note: candidate is: 
In file included from /usr/include/c++/4.7/string:54:0, 
       from articles.cc:2: 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template argument deduction/substitution failed: 
articles.cc:24:9: note: mismatched types ‘const std::basic_string<_CharT, _Traits, _Alloc>’ and ‘const char [16]’ 
articles.cc:24:43: error: passing ‘const Article’ as ‘this’ argument of ‘std::string Article::getReference()’ discards qualifiers [-fpermissive] 
articles.cc: In member function ‘void Stylo::Afficher(std::ostream&) const’: 
articles.cc:67:9: error: no match for ‘operator<<’ in ‘os << " ; couleur = "’ 
articles.cc:67:9: note: candidate is: 
In file included from /usr/include/c++/4.7/string:54:0, 
       from articles.cc:2: 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template argument deduction/substitution failed: 
articles.cc:67:9: note: mismatched types ‘const std::basic_string<_CharT, _Traits, _Alloc>’ and ‘const char [14]’ 
articles.cc:67:39: error: passing ‘const Stylo’ as ‘this’ argument of ‘std::string Stylo::getCouleur()’ discards qualifiers [-fpermissive] 
articles.cc: In member function ‘void Ramette::Afficher(std::ostream&) const’: 
articles.cc:79:9: error: no match for ‘operator<<’ in ‘os << " ; grammage = "’ 
articles.cc:79:9: note: candidate is: 
In file included from /usr/include/c++/4.7/string:54:0, 
       from articles.cc:2: 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template argument deduction/substitution failed: 
articles.cc:79:9: note: mismatched types ‘const std::basic_string<_CharT, _Traits, _Alloc>’ and ‘const char [15]’ 
articles.cc:79:41: error: passing ‘const Ramette’ as ‘this’ argument of ‘int Ramette::getGrammage()’ discards qualifiers [-fpermissive] 
articles.cc: At global scope: 
articles.cc:84:9: error: expected constructor, destructor, or type conversion before ‘(’ token 
articles.cc: In member function ‘virtual std::string Lot::getDescriptif() const’: 
articles.cc:91:26: error: invalid operands of types ‘const char*’ and ‘const char [3]’ to binary ‘operator+’ 
articles.cc: In member function ‘void Lot::Afficher(std::ostream&) const’: 
articles.cc:124:9: error: no match for ‘operator<<’ in ‘os << " ;reduction = "’ 
articles.cc:124:9: note: candidate is: 
In file included from /usr/include/c++/4.7/string:54:0, 
       from articles.cc:2: 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::basic_string<_CharT, _Traits, _Alloc>&) 
/usr/include/c++/4.7/bits/basic_string.h:2750:5: note: template argument deduction/substitution failed: 
articles.cc:124:9: note: mismatched types ‘const std::basic_string<_CharT, _Traits, _Alloc>’ and ‘const char [15]’ 

필자가 볼 수 있듯이, 컴파일러는 연산자 >> 오버로딩에 사용되는 Afficher 메서드로 수행중인 작업을 좋아하지 않습니다. 내가 도대체 ​​뭘 잘못하고있는 겁니까?

Answer 1

일부 문제 :

• STYLO :: getCouleur()

• Ramette :: getGrammage을 (에서 const되지 않음)이 두입니다

을에서 const되지 않는다 내가 처음 발견 한 것들

Answer 2

과부하 operator<<은 비회원 기능으로서, 저로서는 그렇지 않습니다. 광 기능. 이 방법은 왼쪽에서가 아니라 연산자의 오른쪽에 객체를 놓을 수있는 유일한 방법입니다 (클래스 std::ostream을 변경할 수 없음).

편집 :하지만 비 멤버 함수가 차례로 가상 멤버 함수를 호출 할 수 있습니다 ...

헤더 파일 :

class Article { 
public: 
    virtual void Afficher(std::ostream& os) const; 
    //... 
}; 
std::ostream& operator<<(std::ostream& os, const Article& art); 

class ArticleUnitaire : public Article { 
public: 
    virtual void Afficher(std::ostream& os) const; 
    //... 
}; 

inline std::ostream& operator<<(std::ostream& os, const Article& art) { 
    art.Afficher(os); 
    return os; 
} 

소스 파일 :

void Article::Afficher(std::ostream& os) const { 
    //... 
} 

void ArticleUnitaire::Afficher(std::ostream& os) const { 
    Article::Afficher(os); 
    //Other data... 
}