`std :: stringstream :: operator >>()` ne peut pas décaper le type de modèle

Question

J'essaye d'écrire une fonction d'analyseur de chaîne générique en utilisant la classe std::ostringstream.

#include <iostream> 
#include <sstream> 
#include <string> 

template <class ValueType, class CharType> 
ValueType parse_string(const std::basic_string<CharType> & String) 
{ 
    std::basic_ostringstream<CharType> oss(String); 
    ValueType Value; 
    oss >> Value; // ERROR HERE! 
    return Value; 
} 

int wmain(int argc, wchar_t *argv[]/*, wchar_t *envp[]*/) 
{ 
    const std::string SString("3.14"); 
    std::cout << "SString : " << SString << std::endl; 
    std::cout << "int  : " << parse_string<int>(SString) << std::endl; 
    std::cout << "double : " << parse_string<double>(SString) << std::endl; 

    const std::wstring WString(L"2.718"); 
    std::wcout << L"WString : " << WString << std::endl; 
    std::wcout << L"int  : " << parse_string<int>(WString) << std::endl; 
    std::wcout << L"double : " << parse_string<double>(WString) << std::endl; 

    return 0; 
} 

Je reçois les erreurs suivantes pour la ligne marquée.

Error C2676 binary '>>': 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' does not define this operator or a conversion to a type acceptable to the predefined operator 
Error C2678 binary '>>': no operator found which takes a left-hand operand of type 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' (or there is no acceptable conversion) 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,_Elem *)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,_Elem &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,signed char *)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,signed char &)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char *)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char &)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &&,_Ty &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &&' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &&,std::basic_string<_Elem,_Traits,_Alloc> &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &&' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,std::basic_string<_Elem,_Traits,_Alloc> &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' 
Error C2676 binary '>>': 'std::basic_ostringstream<char,std::char_traits<char>,std::allocator<char>>' does not define this operator or a conversion to a type acceptable to the predefined operator 
Error C2678 binary '>>': no operator found which takes a left-hand operand of type 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' (or there is no acceptable conversion) 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,_Elem *)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,_Elem &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,signed char *)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,signed char &)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char *)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<char,_Traits> &std::operator >>(std::basic_istream<char,_Traits> &,unsigned char &)': could not deduce template argument for 'std::basic_istream<char,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &&,_Ty &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &&' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &&,std::basic_string<_Elem,_Traits,_Alloc> &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &&' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 
Error C2784 'std::basic_istream<_Elem,_Traits> &std::operator >>(std::basic_istream<_Elem,_Traits> &,std::basic_string<_Elem,_Traits,_Alloc> &)': could not deduce template argument for 'std::basic_istream<_Elem,_Traits> &' from 'std::basic_ostringstream<wchar_t,std::char_traits<wchar_t>,std::allocator<wchar_t>>' 

Qu'est-ce qui ne va pas dans mon code?

Answer 1

basic_ostringstream a pas opérateur <<>> http://en.cppreference.com/w/cpp/io/basic_ostringstream