operator<<(std::basic_ostream)

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

 

Input/output library

I/O manipulators

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

strstreambuf (deprecated)

Streams

Abstractions

ios_base

basic_ios

basic_istream

basic_ostream

basic_iostream

File I/O

basic_ifstream

basic_ofstream

basic_fstream

String I/O

basic_istringstream

basic_ostringstream

basic_stringstream

Array I/O

istrstream (deprecated)

ostrstream (deprecated)

strstream (deprecated)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

 

std::basic_ostream

Global objects
cout wcout	cerr wcerr	clog wclog
Member functions
basic_ostream::basic_ostream
basic_ostream::~basic_ostream
basic_ostream::operator= (C++11)
Formatted input
basic_ostream::operator<<
Unformatted input
basic_ostream::put
basic_ostream::write
Positioning
basic_ostream::tellp
basic_ostream::seekp
Miscellaneous
basic_ostream::flush
basic_ostream::swap (C++11)
Member classes
basic_ostream::sentry
Non-member functions
operator<<(std::basic_ostream)

 

}}

	(1)
template< class CharT, class Traits> basic_ostream<CharT,Traits>& operator<<( basic_ostream<CharT,Traits>& os,                                          CharT ch );
template< class CharT, class Traits> basic_ostream<CharT,Traits>& operator<<( basic_ostream<CharT,Traits>& os,                                          char ch );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,Traits>& os,                                         char ch );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,Traits>& os,                                         signed char ch );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,Traits>& os,                                         unsigned char ch );
		(2)
template< class CharT, class Traits > basic_ostream<CharT,Traits>& operator<<( basic_ostream<CharT,Traits>& os,                                          const CharT* s );
template< class CharT, class Traits > basic_ostream<CharT,Traits>& operator<<( basic_ostream<CharT,Traits>& os,                                          const char* s );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,Traits>& os,                                           const char* s );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,Traits>& os,                                         const signed char* s );
template< class Traits > basic_ostream<char,Traits>& operator<<( basic_ostream<char,traits>& os,                                         const unsigned char* s );
template< class CharT, class Traits, class T > basic_ostream< charT, traits >& operator<<( basic_ostream<CharT,Traits>&& os,                                             const T& value );			(3)	(since C++11)

Inserts a character or a character string.

1) Behaves as an FormattedOutputFunction. After constructing and checking the sentry object, inserts the character ch. If the type of the character is not CharT, it is first converted with os.widen(ch). Padding is determined as if by Stage 3 of num_put::put(). After insertion, width(0) is called to cancel the effects of std::setw, if any.

2) Behaves as an FormattedOutputFunction. After constructing and checking the sentry object, inserts successive characters from the character array whose first element is pointed to by s.

• for the first and third overloads (where CharT matches the type of ch), exactly traits::length(s) characters are inserted.
• for the second overload, exactly std::char_traits<char>::length(s) characters are inserted.
• for the last two overloads, exactly traits::length(reinterpret_cast<const char*>(s)) are inserted.

Padding is determined as if by Stage 3 of num_put::put(). All characters are widened using os.widen() before insertion. After insertion, width(0) is called to cancel the effects of std::setw, if any.

3) Calls the appropriate insertion operator, given an rvalue reference to an output stream object (equivalent to os << value).

Parameters

os	-	output stream to insert data to
ch	-	reference to a character to insert
s	-	pointer to a character string to insert

Return value

st

Example

run this code

#include <iostream>
#include <sstream>
 
int main()
{
    std::cout << "Hello, world" // the const char* overload
              << '\n';          // the char overload
    std::string s = (std::ostringstream() << 1.2).str(); // rvalue overload
    std::cout << s << '\n';
}

Output:

Hello, world
1.2

See also

operator<<	inserts formatted data (public member function)