std::ios_base::xalloc
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<tbody> </tbody> static int xalloc(); |
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Gibt eine einzigartige (Programm-weit) Indexwert, verwendet werden, um ein
long und ein zugegriffen werden kann void* Elemente in die private Lagerhaltung durch den Aufruf iword() und pword(). Der Aufruf xalloc keinen Speicher .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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Parameter
(None)
Original:
(none)
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Rückgabewert
eindeutige Ganzzahl für die Verwendung als PWord / iword Index
Original:
unique integer for use as pword/iword index
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Beispiel
Verwendet Basisklasse PWord Speicher für Laufzeittyp Identifikation von abgeleiteten Stream-Objekten .
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]
Siehe auch
die Größe der privaten Lagerhaltung bei Bedarf und Zugang zum void* Element am angegebenen IndexOriginal: resizes the private storage if necessary and access to the void* element at the given indexThe text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) | |
die Größe der privaten Lagerhaltung bei Bedarf und Zugang zum long Element am angegebenen IndexOriginal: resizes the private storage if necessary and access to the long element at the given indexThe text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) | |