27 Input/output library [input.output]

27.7 Formatting and manipulators [iostream.format]

27.7.2 Input streams [input.streams]

27.7.2.2 Formatted input functions [istream.formatted]

27.7.2.2.3 basic_istream::operator>> [istream::extractors]

basic_istream<charT,traits>& operator>> (basic_istream<charT,traits>& (*pf)(basic_istream<charT,traits>&));

1

Effects: None. This extractor does not behave as a formatted input function (as described in [istream.formatted.reqmts].)

2

Returns: pf(*this).315

basic_istream<charT,traits>& operator>> (basic_ios<charT,traits>& (*pf)(basic_ios<charT,traits>&));

3

Effects: Calls pf(*this). This extractor does not behave as a formatted input function (as described in [istream.formatted.reqmts]).

4

Returns: *this.

basic_istream<charT,traits>& operator>> (ios_base& (*pf)(ios_base&));

5

Effects: Calls pf(*this).316 This extractor does not behave as a formatted input function (as described in [istream.formatted.reqmts]).

6

Returns: *this.

template<class charT, class traits> basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>& in, charT* s); template<class traits> basic_istream<char,traits>& operator>>(basic_istream<char,traits>& in, unsigned char* s); template<class traits> basic_istream<char,traits>& operator>>(basic_istream<char,traits>& in, signed char* s);

7

Effects: Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of in. After a sentry object is constructed, operator>> extracts characters and stores them into successive locations of an array whose first element is designated by s. If width() is greater than zero, n is width(). Otherwise n is the number of elements of the largest array of char_type that can store a terminating charT(). n is the maximum number of characters stored.

8

Characters are extracted and stored until any of the following occurs:

  • (8.1)

    n-1 characters are stored;

  • (8.2)

    end of file occurs on the input sequence;

  • (8.3)

    ct.is(ct.space,c) is true for the next available input character c, where ct is use_facet<ctype<charT> >(in.getloc()).

9

operator>> then stores a null byte (charT()) in the next position, which may be the first position if no characters were extracted. operator>> then calls width(0).

10

If the function extracted no characters, it calls setstate(failbit), which may throw ios_base::failure ([iostate.flags]).

11

Returns: in.

template<class charT, class traits> basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>& in, charT& c); template<class traits> basic_istream<char,traits>& operator>>(basic_istream<char,traits>& in, unsigned char& c); template<class traits> basic_istream<char,traits>& operator>>(basic_istream<char,traits>& in, signed char& c);

12

Effects: Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of in. After a sentry object is constructed a character is extracted from in, if one is available, and stored in c. Otherwise, the function calls in.setstate(failbit).

13

Returns: in.

basic_istream<charT,traits>& operator>> (basic_streambuf<charT,traits>* sb);

14

Effects: Behaves as an unformatted input function (as described in [istream.unformatted], paragraph 1). If sb is null, calls setstate(failbit), which may throw ios_base::failure ([iostate.flags]). After a sentry object is constructed, extracts characters from *this and inserts them in the output sequence controlled by sb. Characters are extracted and inserted until any of the following occurs:

  • (14.1)

    end-of-file occurs on the input sequence;

  • (14.2)

    inserting in the output sequence fails (in which case the character to be inserted is not extracted);

  • (14.3)

    an exception occurs (in which case the exception is caught).

15

If the function inserts no characters, it calls setstate(failbit), which may throw ios_base::failure ([iostate.flags]). If it inserted no characters because it caught an exception thrown while extracting characters from *this and failbit is on in exceptions() ([iostate.flags]), then the caught exception is rethrown.

16

Returns: *this.

314)

See, for example, the function signature ws(basic_istream&) ([istream.manip]).

315)

See, for example, the function signature dec(ios_base&) ([basefield.manip]).