C++ enum i używanie ich do wprowadzania danych przez użytkownika

Question

Mam wyliczenie w moim kodzie, które jest następujące: enum Status {In-Active, Active};. Obiekt statusu jest przekazywany do obiektu Person jako parametru, więc chcę, aby użytkownik wprowadził Aktywne lub Aktywne i zapisał je w zmiennej Status. Jak mogę to zrobić? Próbowałem go na początku, ale nie działało.

Oto mój kod:

#include <iostream> 

using namespace std; 

enum Status {InActive, Active}; 

class Person { 
    private: 
     string name; 
     int age; 
     Status status; 

    public: 
     Person (const string &_name, const int _age, const Status _status) : name(_name), age(_age), status(_status) {} 

     string &getName() { return name; } 
     int getAge() { return age; } 
     Status getStatus() { return status; } 

     void setName (const string &_name) { name = _name; } 
     void setAge (const int _age) { age = _age; } 
     void setStatus (const Status _status) { status = _status; } 
}; 

//////////////////////////////////////////////////////////////////////////////// 
///////////////////////////////// Main Method ////////////////////////////////// 
//////////////////////////////////////////////////////////////////////////////// 

int main() { 
    string name; 
    int age; 
    Status status; 

    cout << "Enter a name: "; getline(cin, name); 
    cout << "Enter age: "; cin >> age; 
    cout << "Enter status: "; cin >> status; 

    Person p(name, age, status); 

    return 0; 
} 

i tu jest błąd mam (to jest dziennik budowy):

Compiling: C:\Users\KiKo-SaMa\Desktop\C++\Person.cpp 
C:\Users\KiKo-SaMa\Desktop\C++\Person.cpp: In function 'int main()': 
C:\Users\KiKo-SaMa\Desktop\C++\Person.cpp:36:38: error: no match for 'operator>>' in 'std::cin >> status' 
C:\Users\KiKo-SaMa\Desktop\C++\Person.cpp:36:38: note: candidates are: 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:122:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__istream_type& (*)(std::basic_istream<_CharT, _Traits>::__istream_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:122:7: note: no known conversion for argument 1 from 'Status' to 'std::basic_istream<char>::__istream_type& (*)(std::basic_istream<char>::__istream_type&) {aka std::basic_istream<char>& (*)(std::basic_istream<char>&)}' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:126:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__ios_type& (*)(std::basic_istream<_CharT, _Traits>::__ios_type&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>, std::basic_istream<_CharT, _Traits>::__ios_type = std::basic_ios<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:126:7: note: no known conversion for argument 1 from 'Status' to 'std::basic_istream<char>::__ios_type& (*)(std::basic_istream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:133:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(std::ios_base& (*)(std::ios_base&)) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:133:7: note: no known conversion for argument 1 from 'Status' to 'std::ios_base& (*)(std::ios_base&)' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:169:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(bool&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:169:7: note: no known conversion for argument 1 from 'Status' to 'bool&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:173:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(short int&) [with _CharT = char, _Traits = std::char_traits<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:173:7: note: no known conversion for argument 1 from 'Status' to 'short int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:176:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(short unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:176:7: note: no known conversion for argument 1 from 'Status' to 'short unsigned int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:180:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(int&) [with _CharT = char, _Traits = std::char_traits<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:180:7: note: no known conversion for argument 1 from 'Status' to 'int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:183:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:183:7: note: no known conversion for argument 1 from 'Status' to 'unsigned int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:187:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:187:7: note: no known conversion for argument 1 from 'Status' to 'long int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:191:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:191:7: note: no known conversion for argument 1 from 'Status' to 'long unsigned int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:196:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:196:7: note: no known conversion for argument 1 from 'Status' to 'long long int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:200:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long long unsigned int&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:200:7: note: no known conversion for argument 1 from 'Status' to 'long long unsigned int&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:205:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(float&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:205:7: note: no known conversion for argument 1 from 'Status' to 'float&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:209:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(double&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:209:7: note: no known conversion for argument 1 from 'Status' to 'double&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:213:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(long double&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:213:7: note: no known conversion for argument 1 from 'Status' to 'long double&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:217:7: note: std::basic_istream<_CharT, _Traits>::__istream_type& std::basic_istream<_CharT, _Traits>::operator>>(void*&) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__istream_type = std::basic_istream<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:217:7: note: no known conversion for argument 1 from 'Status' to 'void*&' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:241:7: note: std::basic_istream<_CharT, _Traits>& std::basic_istream<_CharT, _Traits>::operator>>(std::basic_istream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char, _Traits = std::char_traits<char>, std::basic_istream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>] 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:241:7: note: no known conversion for argument 1 from 'Status' to 'std::basic_istream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}' 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/basic_string.tcc:998:5: note: template<class _CharT, class _Traits, class _Alloc> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, std::basic_string<_CharT, _Traits, _Alloc>&) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/istream.tcc:957:5: note: template<class _CharT2, class _Traits2> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT2*) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/bits/istream.tcc:925:5: note: template<class _CharT, class _Traits> std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&, _CharT&) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:709:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char&) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:714:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char&) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:756:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, unsigned char*) 
c:\mingw\bin\../lib/gcc/mingw32/4.6.2/include/c++/istream:761:5: note: template<class _Traits> std::basic_istream<char, _Traits>& std::operator>>(std::basic_istream<char, _Traits>&, signed char*) 
Process terminated with status 1 (0 minutes, 0 seconds) 
43 errors, 0 warnings 

skąd mój kod nie udać? Dzięki

Answer 1

nie można odczytać enum wartości bezpośrednio, musisz się std::map który mapuje dane wprowadzone przez użytkownika do wartości enum.

std::map<std::string,Status> m; 
m["In-Active"] = In-Active; 
m["Active"] = Active; 

std::string sstatus; 
cin >> sstatus; 
Status status = m[sstatus]; 

Answer 2

• Enum obiekty są przetwarzane w czasie kompilacji i może zawierać tylko wartości stałych całkowitych.

• Osoba p (imię, wiek, status); // Tutaj, bez użycia obiektu statusu, powinieneś wysłać wartość bezpośrednio "In-Active" lub "Active". W związku z tym nie będzie żadnych danych wejściowych od użytkownika dotyczących pola stanu.

enum Status {Inaktywny, aktywny};

• Tutaj Status jest klasą wyliczeniową, a każdy utworzony obiekt zawierałby wartości "Nieaktywne" lub "Aktywne". Jeśli spróbujesz przypisać inną wartość, pojawi się błąd kompilatora.

Status statusu;

• Tutaj status jest utworzonym obiektem enum i zawiera wartość śmieci.

cout < < "Wprowadź status:"; cin >> status;

• Tutaj pytasz użytkownika o dane wejściowe dla obiektu enum, który jest całkowicie nieważny dla kompilatora.

Answer 3

Można również zawrzeć wyliczenie wewnątrz klasy i zapewnić operatorowi >>. Jest to zmodyfikowany przykład z tego linku http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/Type_Safe_Enum

#include <iostream> 

template<typename def> 
class safe_enum : public def 
{ 
public: 
    int val; 
    safe_enum(int v) : val(v) {} 
// inner underlying() const { return val; } 
    bool operator == (const safe_enum & s) const { return this->val == s.val; } 
    bool operator != (const safe_enum & s) const { return this->val != s.val; } 
    bool operator < (const safe_enum & s) const { return this->val < s.val; } 
    bool operator <= (const safe_enum & s) const { return this->val <= s.val; } 
    bool operator > (const safe_enum & s) const { return this->val > s.val; } 
    bool operator >= (const safe_enum & s) const { return this->val >= s.val; } 
}; 

struct status_def { 
    enum type { NoValue, InActive, Active }; 
}; 
typedef safe_enum<status_def> Status; 

std::istream& operator>>(std::istream& Istr, Status& other) 
{ 
    std::cout << "Enter Status value: " << std::endl; 
    //here the logic to handle input error 
    Istr >> other.val; 
    return Istr; 
} 

std::ostream& operator<<(std::ostream& os,const Status& toPrint) 
{ 
    if (toPrint.val == Status::Active) 
     return os << "Active"; 
    if (toPrint.val == Status::NoValue) 
     return os << "NoValue"; 
    if (toPrint.val == Status::InActive) 
     return os << "InActive"; 
    throw; 
} 

int main(void) 
{ 
    Status test(Status::NoValue); 
    std::cout << test << std::endl; 
    std::cin >> test; 
    std::cout << test << std::endl; 
}