Espaços nominais
Variantes
Acções

std::basic_streambuf::underflow

Da cppreference.com
< cpp‎ | io‎ | basic streambuf

 
 
De entrada / saída da biblioteca
I / O manipuladores
C estilo de I / O
Buffers
Original:
Buffers
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf
basic_filebuf
basic_stringbuf
strstreambuf(obsoleta)
Streams
Original:
Streams
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Abstrações
Original:
Abstractions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ios_base
basic_ios
basic_istream
basic_ostream
basic_iostream
File I / O
Original:
File I/O
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_ifstream
basic_ofstream
basic_fstream
Cordas I / O
Original:
String I/O
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_istringstream
basic_ostringstream
basic_stringstream
Matriz de I / O
Original:
Array I/O
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
istrstream(obsoleta)
ostrstream(obsoleta)
strstream(obsoleta)
Tipos
Original:
Types
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
streamoff
streamsize
fpos
Interface de categoria de erro
Original:
Error category interface
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
iostream_category(C++11)
io_errc(C++11)
 
std::basic_streambuf
Membro funções públicas
Original:
Public member functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::~basic_streambuf
Localidades
Original:
Locales
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::pubimbue
basic_streambuf::getloc
Posicionamento
Original:
Positioning
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::pubsetbuf
basic_streambuf::pubseekoff
basic_streambuf::pubseekpos
basic_streambuf::pubsync
Obter área
Original:
Get area
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::in_avail
basic_streambuf::snextc
basic_streambuf::sbumpc
basic_streambuf::sgetc
basic_streambuf::sgetn
Coloque área
Original:
Put area
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::sputc
basic_streambuf::sputn
Putback
Original:
Putback
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::sputbackc
basic_streambuf::sungetc
Protegido funções de membro
Original:
Protected member functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::basic_streambuf
basic_streambuf::operator=(C++11)
basic_streambuf::swap(C++11)
Localidades
Original:
Locales
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::imbue
Posicionamento
Original:
Positioning
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::setbuf
basic_streambuf::seekoff
basic_streambuf::seekpos
basic_streambuf::sync
Obter área
Original:
Get area
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::showmanyc
basic_streambuf::underflow
basic_streambuf::uflow
basic_streambuf::xsgetn
basic_streambuf::eback
basic_streambuf::gptr
basic_streambuf::egptr
basic_streambuf::gbump
basic_streambuf::setg
Coloque área
Original:
Put area
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::xsputn
basic_streambuf::overflow
basic_streambuf::pbase
basic_streambuf::pptr
basic_streambuf::epptr
basic_streambuf::pbump
basic_streambuf::setp
Putback
Original:
Putback
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
basic_streambuf::pbackfail
 
int_type underflow();
Garante que pelo menos um caracter está disponível na área de entrada, actualizando os ponteiros para a área de entrada (se necessário). Retorna o valor de que o personagem de sucesso ou fracasso em traits::eof().
Original:
Ensures that at least one character is available in the input area by updating the pointers to the input area (if needed). Returns the value of that character on success or traits::eof() on failure.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
A função pode atualizar gptr, egptr e eback ponteiros para definir a localização dos dados recém-carregados (se houver). Em caso de falha, a função que assegura quer gptr() == nullptr ou gptr() == egptr.
Original:
The function may update gptr, egptr and eback pointers to define the location of newly loaded data (if any). On failure, the function ensures that either gptr() == nullptr or gptr() == egptr.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
A versão da classe base da função não faz nada. As classes derivadas podem substituir essa função para permitir atualizações para a área get no caso de exaustão.
Original:
The base class version of the function does nothing. The derived classes may override this function to allow updates to the get area in the case of exhaustion.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Índice

[editar] 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.

[editar] Valor de retorno

O valor do caractere apontado pelo ponteiro' chegar após a chamada de sucesso, ou de outra forma traits::eof().
Original:
The value of the character pointed to by the get pointer after the call on success, or traits::eof() otherwise.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
A versão da classe base da função chama traits::eof().
Original:
The base class version of the function calls traits::eof().
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Nota

As funções públicas de std::streambuf chamar esta função somente se gptr() == nullptr ou gptr() >= egptr().
Original:
The public functions of std::streambuf call this function only if gptr() == nullptr or gptr() >= egptr().
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Exemplo

[edit]
#include <iostream>
#include <sstream>
 
class null_filter_buf : public std::streambuf {
    std::streambuf* src;
    char ch; // single-byte buffer
protected:
    int underflow() {
        while( (ch= src->sbumpc()) == '\0') ; // skip zeroes
        setg(&ch, &ch, &ch+1); // make one read position available
        return ch; // may return EOF
    }
public:
    null_filter_buf(std::streambuf* buf) : src(buf) {
        setg(&ch, &ch+1, &ch+1); // buffer is initially full
    }
};
 
void filtered_read(std::istream& in)
{
    std::streambuf* orig = in.rdbuf();
    null_filter_buf buf(orig);
    in.rdbuf(&buf);
    for(char c; in.get(c); )
            std::cout << c;
    in.rdbuf(orig);
}
 
int main()
{
    char a[] = "This i\0s \0an e\0\0\0xample";
    std::istringstream in(std::string(std::begin(a), std::end(a)));
    filtered_read(in);
}

Output:

This is an example

[editar] Veja também

[virtual]
lê caracteres da seqüência de entrada associado à área de get e avança o ponteiro seguinte
Original:
reads characters from the associated input sequence to the get area and advances the next pointer
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(virtual protegido função de membro) [edit]
[virtual]
escreve caracteres para a seqüência de saída associado da área de venda
Original:
writes characters to the associated output sequence from the put area
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(virtual protegido função de membro) [edit]