aucune correspondance pour 'opérateur <<' dans 'std :: Cout << :: operator ++ (int) (0)'

#include <cstdio> 
#include <cmath> 
#include <cstring> 
#include <ctime> 
#include <iostream> 
#include <algorithm> 
#include <set> 
#include <map> 
#include <vector> 
#include <sstream> 
#include <typeinfo> 

#define debug(args...) // Just strip off all debug tokens 
using namespace std; 
// CUT begin 
#define debug(args...) {dbg,args;cout<<endl;} 
struct debugger{template<typename T> debugger& operator ,(const T& v){cout<<v<<" ";return *this;}}dbg; 
template <typename T1,typename T2> inline ostream& operator<<(ostream& os,const pair<T1,T2>& p){return os<<"("<<p.first<<", "<<p.second<<")";} 
template<typename T>inline ostream&operator<<(ostream& os,const vector<T>& v){string delim="[";for(unsigned int i=0;i < v.size();i++){os<<delim<<v[i];delim=", ";}return os<<"]";} 
template<typename T>inline ostream&operator<<(ostream& os,const set<T>& v){string delim="[";for (typename set<T>::const_iterator ii=v.begin();ii!=v.end();++ii){os<<delim<<*ii;delim=", ";}return os<<"]";} 
template<typename T1,typename T2>inline ostream&operator<<(ostream& os,const map<T1,T2>& v){string delim="[";for (typename map<T1,T2>::const_iterator ii=v.begin();ii!=v.end();++ii){os<<delim<<*ii;delim=", ";}return os<<"]";} 
// CUT end 


class Vehicle 
{ 
public: 
    int n; 
    Vehicle(int n):n(n){cout<<"Ctor Vehicle "<<n<<endl;} 
    Vehicle(Vehicle& v):n(v.n){cout<<"Copy Ctor Vehicle "<<n<<endl;} 
    virtual ~Vehicle(){cout<<"Dtor Vehicle "<<n<<endl;} 
    virtual ostream& dump(ostream& os){return os<<"Vehicle("<<n<<")";} 
    string to_str(){stringstream s; dump(s); return s.str();} 
    Vehicle& operator++(){n++;return *this;} 
    Vehicle operator++(int x){Vehicle v(*this); operator++(); return v;} 
}; 

class Car: public Vehicle 
{ 
public: 
    Car(int n): Vehicle(n){cout<<"Ctor Car "<<n<<endl;} 
    virtual ~Car(){cout<<"Dtor Car "<<n<<endl;} 
    virtual ostream& dump(ostream& os){return os<<"Car("<<n<<")";} 
    Car operator++(int x){Car v(*this); operator++(); return v;} 
    Car& operator++(){n++; return *this;} 
    /* data */ 
}; 
ostream& operator<<(ostream& os, Vehicle& v) 
{ 
    return v.dump(os); 
} 

int main(int argc, char const *argv[]) 
{ 
    Car c(10); 
    // cout<<c++<<endl; 
    cout<<c++<<endl; 
    return 0; 
}

la ligne cout<<c++<<endl; provoque l'erreur suivante:aucune correspondance pour 'opérateur <<' dans 'std :: Cout << :: operator ++ (int) (0)'

C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:16:0: warning: "debug" redefined [enabled by default] 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:13:0: note: this is the location of the previous definition 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp: In function 'int main(int, const char**)': 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:57:9: error: no match for 'operator<<' in 'std::cout << Car::operator++(int)(0)' 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:57:9: note: candidates are: 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:110:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:110:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:119:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>, std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:119:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:129:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:129:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'std::ios_base& (*)(std::ios_base&)' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:167:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:167:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'long int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:171:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:171:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'long unsigned int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:175:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:175:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'bool' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:93:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char, _Traits = std::char_traits<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:93:5: note: no known conversion for argument 1 from 'Car {aka Car}' to 'short int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:182:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:182:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'short unsigned int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:107:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:107:5: note: no known conversion for argument 1 from 'Car {aka Car}' to 'int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:193:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:193:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'unsigned int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:202:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:202:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'long long int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:206:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:206:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'long long unsigned int' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:211:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:211:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'double' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:215:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:215:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'float' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:223:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:223:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'long double' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:227:7: note: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:227:7: note: no known conversion for argument 1 from 'Car {aka Car}' to 'const void*' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:121:5: note: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>] 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:121:5: note: no known conversion for argument 1 from 'Car {aka Car}' to 'std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}' 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:18:95: note: template<class T1, class T2> std::ostream& operator<<(std::ostream&, const std::pair<_T1, _T2>&) 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:19:77: note: template<class T> std::ostream& operator<<(std::ostream&, const std::vector<T>&) 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:20:74: note: template<class T> std::ostream& operator<<(std::ostream&, const std::set<T>&) 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:21:91: note: template<class T1, class T2> std::ostream& operator<<(std::ostream&, const std::map<T1, T2>&) 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:48:10: note: std::ostream& operator<<(std::ostream&, Vehicle&) 
C:\Users\Rajat\Documents\GitHub\interview-preparation\cpp_test.cpp:48:10: note: no known conversion for argument 2 from 'Car {aka Car}' to 'Vehicle&' 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:528:77: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:523:75: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:510:5: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/ostream.tcc:323:70: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:493:72: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:473:70: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:468:68: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:462:61: note: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:456:63: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/ostream:451:65: note: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT) 
c:\program files (x86)\dev-cpp\mingw64\bin\../lib/gcc/x86_64-w64-mingw32/4.6.1/include/c++/bits/basic_string.h:2694:59: 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>&) 
[Finished in 1.2s with exit code 1]

Pourquoi est-ce une erreur est survenue?

Source

2013-06-15 prongs

Votre operator + renvoie un type temporaire de type Car, qui ne peut pas être lié à une référence lvalue (qui est ce que votre operator << accepte), car les objets temporaires sont rvalues  (plus précisément, prvalues ).

Changer votre opérateur d'insertion dans:

ostream& operator<<(ostream& os, Vehicle const& v) 
//          ^^^^^ 
{ 
    return v.dump(os); 
}

Par conséquent, faire dump() une fonction membre const. Tout cela est logique, car une fonction qui est censé fournir une représentation d'un objet ne devrait pas modifier l'état de cet objet:

class Vehicle 
{ 
    // ... 
    virtual ostream& dump(ostream& os) const {return os<<"Vehicle("<<n<<")";} 
//          ^^^^^ 
    // ... 
}; 

class Car: public Vehicle 
{ 
    // ... 
    virtual ostream& dump(ostream& os) const {return os<<"Car("<<n<<")";} 
//          ^^^^^ 
    // ... 
};

Source

2013-06-15 12:30:53

Je vais avoir besoin d'étudier 'const',' 'lvalue' et rvalue Pour obtenir ce que vous voulez dire. – prongs

@prongs: 'const' est simple: lorsqu'il est appliqué à une fonction membre, comme je l'ai fait dans l'exemple ci-dessus, il promet simplement que la fonction ne modifiera pas l'état de l'objet sur lequel il est appelé. Si vous avez une référence à 'const', comme un' const foo & f' ou 'foo const & f' (qui est le même), cela ne vous permettra pas d'écrire' fm() 'si' m' est un non -const_ member member: une référence 'const' ne doit jamais autoriser les modifications de l'objet référencé, donc vous ne pouvez invoquer que des fonctions membres qui promettent de ne pas le faire (c'est-à-dire des fonctions membres' const'). lvalues et rvalues est une histoire plus complexe –

aucune correspondance pour 'opérateur <<' dans 'std :: Cout << :: operator ++ (int) (0)'

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