std::basic_istream::sentry – cppreference.com

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definiert in Header `<istream>`

`template< class CharT, class Traits = std::char_traits<CharT>> class std::basic_istream<CharT, Traits>::sentry;`

An object of class basic_istream::sentry is constructed in local scope at the beginning of each member function of std::basic_istream that performs input (both formatted and unformatted). Its constructor prepares the input stream: checks if the stream is already in a failed state, flushes the tie()'d output streams, skips leading whitespace if skipws flag is set, and performs other implementation-defined tasks if necessary. All cleanup, if necessary, is performed in the destructor, so that it is guaranteed to happen if exceptions are thrown during input.

Mitglied Typen

Member-Funktionen


(constructor)	baut die Wache object. All der Zubereitung Aufgaben hier fertig sind Original: constructs the sentry object. All the preparation tasks are done here The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) [edit]

(destructor)	finalizes the stream object after formatted input or after exception, if necessary (öffentliche Elementfunktion)

operator= [gelöscht]	nicht kopieren übertragbar Original: not copy assignable The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion)

operator bool	prüft, ob die Vorbereitung der Stream-Objekt erfolgreich war Original: checks if the preparation of the stream object was successful The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) [edit]

Beispiel

#include <iostream>
#include <sstream>

struct Foo {
   char n[5];
};
std::istream& operator>>(std::istream& is, Foo& f)
{
    std::istream::sentry s(is);
    if(s)
        is.read(f.n, 5);
    return is;
}

int main()
{
    std::string input = "   abcde";
    std::istringstream stream(input);
    Foo f;
    stream >> f;
    std::cout.write(f.n, 5);
    std::cout << '\n';
}

Output:

Siehe auch


	Extrakte formatierte Daten Original: extracts formatted data The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (öffentliche Elementfunktion) [edit]

	extrahiert Zeichen und Zeichen-Arrays Original: extracts characters and character arrays The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Funktions-Template) [edit]