Varianti

    operator>><div class="t-tr-text">(Std :: basic_istream)<div class="t-tr-dropdown"><div><div><div class="t-tr-dropdown-arrow-border"></div><div class="t-tr-dropdown-arrow"></div><div class="t-tr-dropdown-h">Original:</div><div class="t-tr-dropdown-orig">(std::basic_istream)</div><div class="t-tr-dropdown-notes">The text has been machine-translated via [http://translate.google.com Google Translate].<br/> You can help to correct and verify the translation. Click [http://en.cppreference.com/w/Cppreference:MachineTranslations here] for instructions.</div></div></div></div></div>

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    <metanoindex/>

     
    C++
     
    Ingresso / libreria di output
    I / O manipolatori
    C-style I / O
    Buffer
    Original:
    Buffers
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    basic_streambuf
    basic_filebuf
    basic_stringbuf
    strstreambuf(deprecato)
    Streams
    Original:
    Streams
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    Astrazioni
    Original:
    Abstractions
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    ios_base
    basic_ios
    basic_istream
    basic_ostream
    basic_iostream
    File I / O
    Original:
    File I/O
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    basic_ifstream
    basic_ofstream
    basic_fstream
    String I / O
    Original:
    String I/O
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    basic_istringstream
    basic_ostringstream
    basic_stringstream
    Array I / O
    Original:
    Array I/O
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    istrstream(deprecato)
    ostrstream(deprecato)
    strstream(deprecato)
    Tipi
    Original:
    Types
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    streamoff
    streamsize
    fpos
    Errore categoria interfaccia
    Original:
    Error category interface
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    iostream_category(C++11)
    io_errc(C++11)
     
    std::basic_istream
    Gli oggetti globali
    Original:
    Global objects
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    cin
    wcin
    Membri funzioni
    Original:
    Member functions
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    basic_istream::basic_istream
    basic_istream::~basic_istream
    basic_istream::operator=(C++11)
    Ingresso formattato
    Original:
    Formatted input
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    basic_istream::operator>>
    Ingresso non formattato
    Original:
    Unformatted input
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    basic_istream::get
    basic_istream::peek
    basic_istream::unget
    basic_istream::putback
    basic_istream::getline
    basic_istream::ignore
    basic_istream::read
    basic_istream::readsome
    basic_istream::gcount
    Posizionamento
    Original:
    Positioning
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    basic_istream::tellg
    basic_istream::seekg
    Varie
    Original:
    Miscellaneous
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    basic_istream::sync
    basic_istream::swap(C++11)
    Membri classi
    Original:
    Member classes
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    basic_istream::sentry
    Non membri funzioni
    Original:
    Non-member functions
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    operator>>(std::basic_istream)
     
    <tbody> </tbody>
    template< class CharT, class Traits > basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>& st, CharT& ch ); template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, signed char& ch ); template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, unsigned char& ch );
    		 (1)
    template< class CharT, class Traits> basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>& st, CharT* s ); template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, signed char* s ); template< class Traits > basic_istream<char,Traits>& operator>>( basic_istream<char,Traits>& st, unsigned char* s );
    		 (2)
    template< class CharT, class Traits, class T > basic_istream<CharT,Traits>& operator>>( basic_istream<CharT,Traits>&& st, T& value );
    		 (3) (dal C++11)
    Esegue operazioni di input dei caratteri.
    Original:
    Performs character input operations.
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    1)

    Estrae un carattere e lo memorizza per ch.
    Original:
    Extracts a character and stores it to ch.
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    2)

    Estrae i caratteri successivi e li memorizza in posizioni successive di un array di caratteri il cui primo elemento è puntato da s. L'estrazione si interrompe se una delle seguenti condizioni:
    Original:
    Extracts successive characters and stores them at successive locations of a character array whose first element is pointed to by s. The extraction stops if one of the following conditions are met:
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    • uno spazio bianco (come determinato dalla sfaccettatura ctype<CharT>) si trova. Il carattere di spazio non viene estratto.
      Original:
      a whitespace character (as determined by the ctype<CharT> facet) is found. The whitespace character is not extracted.
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    • Caratteri this->width() - 1 sono estratti
      Original:
      this->width() - 1 characters are extracted
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    In entrambi i casi, un ulteriore carattere nullo CharT() valore viene memorizzato al termine dell'uscita.
    Original:
    In either case, an additional null character value CharT() is stored at the end of the output.
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    3)

    Chiama l'operatore di estrazione appropriato, dato un riferimento a un oggetto rvalue flusso di input (equivalente a st >> value).
    Original:
    Calls the appropriate extraction operator, given an rvalue reference to an input stream object (equivalent to st >> value).
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    Note

    I (1-2) versioni del gestore si comportano come funzioni di ingresso in formato. Cioè, costruire un oggetto sentry all'inizio che svuota il legame () 'd buffer, se necessario, i controlli per gli errori, e gli estratti ed elimina tutti i caratteri di spazi bianchi a meno che il ios_base :: bandiera skipws è stato cancellato. L'ingresso è utilizzato solo se l'oggetto sentry restituisce true.
    Original:
    The (1-2) versions of the operator behave as formatted input functions. That is, they construct a sentry object at the beginning that flushes the tie()'d buffers if needed, checks for errors, and extracts and discards all leading whitespace characters unless the ios_base::skipws flag was cleared. The input is attempted only if the sentry object returns true.
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    Parametri

    st -
    flusso di input per estrarre i dati da
    Original:
    input stream to extract the data from
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    ch -
    riferimento a un carattere per memorizzare il carattere estratto
    Original:
    reference to a character to store the extracted character to
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    s -
    puntatore a una stringa di caratteri per memorizzare i caratteri estratti
    Original:
    pointer to a character string to store the extracted characters to
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    Valore di ritorno

    st

    Esempio

    #include <iostream>
#include <iomanip>
#include <sstream>

int main()
{
    std::string input = "n greetings";
    std::istringstream stream(input);
    char c;
    const int MAX = 6;
    char cstr[MAX];

    stream >> c >> std::setw(MAX) >> cstr;
    std::cout << "c = " << c << '\n'
              << "cstr = " << cstr << '\n';

    double f;
    std::istringstream("1.23") >> f; // rvalue stream extraction
    std::cout << "f = " << f << '\n';
}

    Output: 

    c = n
cstr = greet
f = 1.23

    Vedi anche
    estratti i dati formattati
    Original:
    extracts formatted data
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    (metodo pubblico) [modifica]