std::basic_filebuf::is_open

<metanoindex/>

 

C++

Linguaggio

Concetti

Libreria di Utilità

Stringhe

Contenitori

Algoritmi

Iteratori

Libreria matematca

Input/output

Localizzazione

Espressioni regolari (C++11)

Operazioni atomicche (C++11)

Multithreading (C++11)

 

Ingresso / libreria di output

I / O manipolatori

C-style I / O

Buffer 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 (deprecato)

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.

Astrazioni 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

String 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

Array 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 (deprecato)

ostrstream (deprecato)

strstream (deprecato)

Tipi 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

Errore categoria interfaccia 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_filebuf

Funzioni membro pubbliche 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_filebuf::basic_filebuf

basic_filebuf::~basic_filebuf

basic_filebuf::operator= (C++11)

basic_filebuf::swap (C++11)

basic_filebuf::is_open

basic_filebuf::open

basic_filebuf::close

Protetto funzioni 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_filebuf::showmanyc

basic_filebuf::underflow

basic_filebuf::uflow

basic_filebuf::pbackfail

basic_filebuf::overflow

basic_filebuf::setbuf

basic_filebuf::seekoff

basic_filebuf::seekpos

basic_filebuf::sync

basic_filebuf::imbue

Non membri funzioni Original: Non-member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

swap(std::basic_filebuf) (C++11)

 

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bool is_open() const;

Restituisce true se la chiamata più recente open() avuto successo e non vi è stata chiamata a close() da allora.

Original:

Returns true if the most recent call to open() succeeded and there has been no call to close() since then.

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Parametri

(Nessuno)

Original:

(none)

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Valore di ritorno

true se il file associato è aperto, altrimenti false.

Original:

true if the associated file is open, false otherwise.

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Note

Questa funzione viene in genere chiamato da std::basic_fstream::is_open.

Original:

This function is typically called by std::basic_fstream::is_open.

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Esempio

#include <fstream>
#include <iostream>

int main()
{
    std::ifstream fs("test.txt");
    std::filebuf fb;
    fb.open("test.txt", std::ios_base::in);
    std::cout << std::boolalpha
              << "direct call: " << fb.is_open() << '\n'
              << "through streambuf: " << fs.rdbuf()->is_open() << '\n'
              << "through fstream: " << fs.is_open() << '\n';
}

Output:

direct call: true
through streambuf: true
through fstream: true

Vedi anche

open	apre un file e lo configura come la sequenza di caratteri associata Original: opens a file and configures it as the associated character sequence The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)
close	svuota il buffer dell'area mettere e chiude il file associato Original: flushes the put area buffer and closes the associated file The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)