std::ios_base::pword
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<metanoindex/>
<tbody> </tbody> void*& pword( int index ); |
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La première, affecte ou redimensionne le stockage privé (tableau dynamique de
void* ou une autre structure de données amovible) suffisamment pour faire index un indice valide, puis renvoie une référence à l'élément de void* le stockage privé à l'indice index . Original:
First, allocates or resizes the private storage (dynamic array of
void* or another indexable data structure) sufficiently to make index a valid index, then returns a reference to the void* element of the private storage with the index index. The text has been machine-translated via Google Translate.
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La référence peut être invalidé par une opération sur cet objet
ios_base, y compris un autre appel à pword(), mais les valeurs enregistrées sont conservées, de sorte que la lecture de pword(index) avec le même indice plus tard, va produire la même valeur (jusqu'à ce que le prochain appel à copyfmt()). La valeur peut être utilisée pour n'importe quel but. L'indice de l'élément doit être obtenu par xalloc(), sinon les collisions avec les autres utilisateurs de ce ios_base peut se produire. De nouveaux éléments sont initialisés à NULL .Original:
The reference may be invalidated by any operation on this
ios_base object, including another call to pword(), but the stored values are retained, so that reading from pword(index) with the same index later will produce the same value (until the next call to copyfmt()). The value can be used for any purpose. The index of the element must be obtained by xalloc(), otherwise collisions with other users of this ios_base may occur. New elements are initialized to NULL.The text has been machine-translated via Google Translate.
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Si l'allocation échoue, appelle
std::basic_ios<>::setstate(badbit) qui peut std::basic_ios::failure jeterOriginal:
If allocation fails, calls
std::basic_ios<>::setstate(badbit) which may throw std::basic_ios::failureThe text has been machine-translated via Google Translate.
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Paramètres
| index | - | valeur de l'indice de l'élément
Original: index value of the element The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Retourne la valeur
une référence à l'élément
Original:
reference to the element
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Exceptions
Peut générer std::ios_base::failure lors du réglage du BadBit .
Original:
May throw std::ios_base::failure when setting the badbit.
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Exemple
Utilise la classe de base motpasse de stockage pour l'identification du type d'exécution d'objets de flux dérivés .
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';
}
Résultat :
cout, narrow-character test
myout, narrow-character test [special handling for mystream]
wcout, wide-character test
mywout, wide-character test [special handling for mystream]
Voir aussi
redimensionne le stockage privé et le cas échéant un accès à l'élément de long à l'index donnéOriginal: 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. (fonction membre publique) | |
[ statique ]Original: static The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
renvoie un entier ensemble du programme unique qui est sûr à utiliser comme indice de motpasse () et iword () Original: returns a program-wide unique integer that is safe to use as index to pword() and iword() The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction membre publique statique) |