std::ios_base::xalloc
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| static int xalloc(); |
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Restituisce un valore unico (programma-wide) indice che può essere utilizzato per accedere a un long e uno void* elementi l'ammasso privato chiamando
iword() e pword(). La chiamata a xalloc non alloca la memoria.Original:
Returns an unique (program-wide) index value that can be used to access one long and one void* elements in the private storage by calling
iword() and pword(). The call to xalloc does not allocate memory.The text has been machine-translated via Google Translate.
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[modifica] Parametri
(Nessuno)
Original:
(none)
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[modifica] Valore di ritorno
intero univoco per uso come pword / iword index
Original:
unique integer for use as pword/iword index
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[modifica] Esempio
Utilizza memorizzazione classe base pword per l'identificazione tipo di runtime oggetti flusso derivati .
Original:
Uses base class pword storage for runtime type identification of derived stream objects.
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#include <iostream> template<class charT, class traits = std::char_traits<charT> > class mystream : public std::basic_ostream<charT, traits> { public: static const int xindex; mystream(std::basic_ostream<charT, traits>& ostr) : std::basic_ostream<charT, traits>(ostr.rdbuf()) { this->pword(xindex) = this; } void myfn() { *this << "[special handling for mystream]"; } }; // each specialization of mystream obtains a unique index from xalloc() template<class charT, class traits> const int mystream<charT, traits>::xindex = std::ios_base::xalloc(); // This I/O manipulator will be able to recognize ostreams that are mystreams // by looking up the pointer stored in pword template<class charT, class traits> std::basic_ostream<charT,traits>& mymanip(std::basic_ostream<charT,traits>& os) { if (os.pword(mystream<charT,traits>::xindex) == &os) static_cast<mystream<charT,traits>&>(os).myfn(); return os; } int main() { std::cout << "cout, narrow-character test " << mymanip << '\n'; mystream<char> myout(std::cout); myout << "myout, narrow-character test " << mymanip << '\n'; std::wcout << "wcout, wide-character test " << mymanip << '\n'; mystream<wchar_t> mywout(std::wcout); mywout << "mywout, wide-character test " << mymanip << '\n'; }
Output:
cout, narrow-character test myout, narrow-character test [special handling for mystream] wcout, wide-character test mywout, wide-character test [special handling for mystream]
[modifica] Vedi anche
| ridimensiona l'ammasso privato e, se necessario, l'accesso all'elemento void* in corrispondenza dell'indice specificato Original: resizes the private storage if necessary and access to the void* element at the given index The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) | |
| ridimensiona l'ammasso privato e, se necessario, l'accesso all'elemento long in corrispondenza dell'indice specificato Original: resizes the private storage if necessary and access to the long element at the given index The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico) | |
