[ostream.inserters]

# 31 Input/output library [[input.output]](./#input.output)

## 31.7 Formatting and manipulators [[iostream.format]](iostream.format#ostream.inserters)

### 31.7.6 Output streams [[output.streams]](output.streams#ostream.inserters)

#### 31.7.6.3 Formatted output functions [[ostream.formatted]](ostream.formatted#ostream.inserters)

#### 31.7.6.3.3 basic_ostream​::​operator<< [ostream.inserters]

[🔗](#lib:operator%3c%3c,basic_ostream)

`basic_ostream& operator<<(basic_ostream& (*pf)(basic_ostream&));
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6581)

*Effects*: None[.](#1.sentence-1)

Does not behave as a formatted output function (as described
in [[ostream.formatted.reqmts]](ostream.formatted.reqmts "31.7.6.3.1 Common requirements"))[.](#1.sentence-2)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6587)

*Returns*: pf(*this)[.](#2.sentence-1)[286](#footnote-286 "See, for example, the function signature endl(basic_­ostream&amp;) ([ostream.manip]).")

[🔗](#lib:operator%3c%3c,basic_ostream_)

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

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6603)

*Effects*: Callspf(*this)[.](#3.sentence-1)

This inserter does not
behave as a formatted output function (as described in [[ostream.formatted.reqmts]](ostream.formatted.reqmts "31.7.6.3.1 Common requirements"))[.](#3.sentence-2)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6610)

*Returns*: *this[.](#4.sentence-1)[287](#footnote-287 "See, for example, the function signature dec(ios_­base&amp;) ([basefield.manip]).")

[🔗](#lib:operator%3c%3c,basic_ostream__)

`basic_ostream& operator<<(ios_base& (*pf)(ios_base&));
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6626)

*Effects*: Callspf(*this)[.](#5.sentence-1)

This inserter does not
behave as a formatted output function (as described in [[ostream.formatted.reqmts]](ostream.formatted.reqmts "31.7.6.3.1 Common requirements"))[.](#5.sentence-2)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6633)

*Returns*: *this[.](#6.sentence-1)

[🔗](#lib:operator%3c%3c,basic_ostream___)

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

[7](#7)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6644)

*Effects*: Behaves as an unformatted output function ([[ostream.unformatted]](ostream.unformatted "31.7.6.4 Unformatted output functions"))[.](#7.sentence-1)

After the sentry object is
constructed, ifsb is null callssetstate(badbit) (which may throwios_base​::​failure)[.](#7.sentence-2)

[8](#8)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6654)

Gets characters from sb and inserts them in*this[.](#8.sentence-1)

Characters are read from sb and inserted until any of the following occurs:

- [(8.1)](#8.1)

end-of-file occurs on the input sequence;

- [(8.2)](#8.2)

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

- [(8.3)](#8.3)

an exception occurs while getting a character from sb[.](#8.sentence-2)

[9](#9)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6670)

If the function inserts no characters, it callssetstate(failbit) (which may throwios_base​::​​failure ([[iostate.flags]](iostate.flags "31.5.4.4 Flags functions")))[.](#9.sentence-1)

If an exception was thrown while extracting a character,
the function setsfailbit in the error state, and iffailbit is set inexceptions() the caught exception is rethrown[.](#9.sentence-2)

[10](#10)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6684)

*Returns*: *this[.](#10.sentence-1)

[🔗](#lib:operator%3c%3c,basic_ostream____)

`basic_ostream& operator<<(nullptr_t);
`

[11](#11)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iostreams.tex#L6695)

*Effects*: Equivalent to:return *this << s; where s is animplementation-defined[NTCTS](defns.ntcts "3.36 NTCTS [defns.ntcts]")[.](#11.sentence-1)

[286)](#footnote-286)[286)](#footnoteref-286)

See, for example, the function signatureendl(basic_ostream&) ([[ostream.manip]](ostream.manip "31.7.6.5 Standard basic_­ostream manipulators"))[.](#footnote-286.sentence-1)

[287)](#footnote-287)[287)](#footnoteref-287)

See, for example, the function signaturedec(ios_base&) ([[basefield.manip]](basefield.manip "31.5.5.3 basefield manipulators"))[.](#footnote-287.sentence-1)