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cppdraft_translate/cppdraft/istream/extractors.md
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[istream.extractors]
# 31 Input/output library [[input.output]](./#input.output)
## 31.7 Formatting and manipulators [[iostream.format]](iostream.format#istream.extractors)
### 31.7.5 Input streams [[input.streams]](input.streams#istream.extractors)
#### 31.7.5.3 Formatted input functions [[istream.formatted]](istream.formatted#istream.extractors)
#### 31.7.5.3.3 basic_istream​::​operator>> [istream.extractors]
[🔗](#lib:operator%3e%3e,basic_istream)
`basic_istream& operator>>(basic_istream& (*pf)(basic_istream&));
`
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4857)
*Effects*: None[.](#1.sentence-1)
This extractor does not behave as a formatted input function
(as described in [[istream.formatted.reqmts]](istream.formatted.reqmts "31.7.5.3.1 Common requirements"))[.](#1.sentence-2)
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4863)
*Returns*: pf(*this)[.](#2.sentence-1)
[274](#footnote-274 "See, for example, the function signature ws(basic_­istream&) ([istream.manip]).")
[🔗](#lib:operator%3e%3e,basic_istream_)
`basic_istream& operator>>(basic_ios<charT, traits>& (*pf)(basic_ios<charT, traits>&));
`
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4879)
*Effects*: Callspf(*this)[.](#3.sentence-1)
This extractor does not behave as a formatted input function
(as described in [[istream.formatted.reqmts]](istream.formatted.reqmts "31.7.5.3.1 Common requirements"))[.](#3.sentence-2)
[4](#4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4886)
*Returns*: *this[.](#4.sentence-1)
[🔗](#lib:operator%3e%3e,basic_istream__)
`basic_istream& operator>>(ios_base& (*pf)(ios_base&));
`
[5](#5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4897)
*Effects*: Callspf(*this)[.](#5.sentence-1)[275](#footnote-275 "See, for example, the function signature dec(ios_­base&amp;) ([basefield.manip]).")
This extractor does not behave as a formatted input function
(as described in [[istream.formatted.reqmts]](istream.formatted.reqmts "31.7.5.3.1 Common requirements"))[.](#5.sentence-2)
[6](#6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4908)
*Returns*: *this[.](#6.sentence-1)
[🔗](#lib:operator%3e%3e,basic_istream___)
`template<class charT, class traits, size_t N>
basic_istream<charT, traits>& operator>>(basic_istream<charT, traits>& in, charT (&s)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, unsigned char (&s)[N]);
template<class traits, size_t N>
basic_istream<char, traits>& operator>>(basic_istream<char, traits>& in, signed char (&s)[N]);
`
[7](#7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4924)
*Effects*: Behaves like a formatted input member (as described in [[istream.formatted.reqmts]](istream.formatted.reqmts "31.7.5.3.1 Common requirements"))
of in[.](#7.sentence-1)
After asentry object is constructed,operator>> extracts characters and stores them intos[.](#7.sentence-2)
Ifwidth() is greater than zero, n ismin(size_t(width()), N)[.](#7.sentence-3)
Otherwise n is N[.](#7.sentence-4)
n is the maximum number of characters stored[.](#7.sentence-5)
[8](#8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4941)
Characters are extracted and stored until any of the following occurs:
- [(8.1)](#8.1)
n - 1 characters are stored;
- [(8.2)](#8.2)
end of file occurs on the input sequence;
- [(8.3)](#8.3)
letting ct be use_facet<ctype<charT>>(in.getloc()),ct.is(ct.space, c) is true[.](#8.sentence-1)
[9](#9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4950)
operator>> then stores a null byte
(charT())
in the next position, which may be the first position if no characters
were extracted[.](#9.sentence-1)
operator>> then callswidth(0)[.](#9.sentence-2)
[10](#10)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4960)
If the function extracted no characters,ios_base​::​failbit is set in the input function's local error state
before setstate is called[.](#10.sentence-1)
[11](#11)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4965)
*Returns*: in[.](#11.sentence-1)
[🔗](#lib:operator%3e%3e,basic_istream____)
`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](#12)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4981)
*Effects*: Behaves like a formatted input member (as described in [[istream.formatted.reqmts]](istream.formatted.reqmts "31.7.5.3.1 Common requirements"))
of in[.](#12.sentence-1)
A character is extracted from in, if one is available, and stored in c[.](#12.sentence-2)
Otherwise,ios_base​::​failbit is set in the input function's local error state
before setstate is called[.](#12.sentence-3)
[13](#13)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L4990)
*Returns*: in[.](#13.sentence-1)
[🔗](#lib:operator%3e%3e,basic_istream_____)
`basic_istream& operator>>(basic_streambuf<charT, traits>* sb);
`
[14](#14)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L5001)
*Effects*: Behaves as an [unformatted input function](istream.unformatted "31.7.5.4 Unformatted input functions [istream.unformatted]")[.](#14.sentence-1)
If sb is null, callssetstate(failbit),
which may throwios_base​::​failure ([[iostate.flags]](iostate.flags "31.5.4.4 Flags functions"))[.](#14.sentence-2)
After a sentry object is constructed, extracts
characters from*this and inserts them in the output sequence controlled by sb[.](#14.sentence-3)
Characters are extracted and inserted until any of the following occurs:
- [(14.1)](#14.1)
end-of-file occurs on the input sequence;
- [(14.2)](#14.2)
inserting in the output sequence fails
(in which case the character to be inserted is not extracted);
- [(14.3)](#14.3)
an exception occurs (in which case the exception is caught)[.](#14.sentence-4)
[15](#15)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L5023)
If the function inserts no characters,ios_base​::​failbit is set in the input function's local error state
before setstate is called[.](#15.sentence-1)
[16](#16)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L5028)
*Returns*: *this[.](#16.sentence-1)
[274)](#footnote-274)[274)](#footnoteref-274)
See, for example, the function signaturews(basic_istream&) ([[istream.manip]](istream.manip "31.7.5.5 Standard basic_­istream manipulators"))[.](#footnote-274.sentence-1)
[275)](#footnote-275)[275)](#footnoteref-275)
See, for example, the function signaturedec(ios_base&) ([[basefield.manip]](basefield.manip "31.5.5.3 basefield manipulators"))[.](#footnote-275.sentence-1)
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