std::ios_base::xalloc
De cppreference.com
 |
This page has been machine-translated from the English version of the wiki using Google Translate.
The translation may contain errors and awkward wording. Hover over text to see the original version. You can help to fix errors and improve the translation. For instructions click here. |
<metanoindex/>
<tbody> </tbody> static int xalloc(); |
||
Retorna um valor (programa de largura) índice exclusivo que pode ser usado para acessar um
long e um void* elementos da armazenagem privada, chamando iword() e pword(). A chamada para xalloc não aloca memória.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.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Parâmetros
(Nenhum)
Original:
(none)
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Valor de retorno
inteiro exclusivo para uso como pword / iword índice
Original:
unique integer for use as pword/iword index
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Exemplo
Usa base de classe de armazenamento pword para identificação do tipo de tempo de execução de objetos de fluxo derivados .
Original:
Uses base class pword storage for runtime type identification of derived stream objects.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
#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';
}
Saída:
cout, narrow-character test
myout, narrow-character test [special handling for mystream]
wcout, wide-character test
mywout, wide-character test [special handling for mystream]
Veja também
redimensiona a armazenagem privada, se necessário e acesso ao elemento void* no índice fornecidoOriginal: 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. (função pública membro) | |
redimensiona a armazenagem privada, se necessário e acesso ao elemento long no índice fornecidoOriginal: 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. (função pública membro) | |