basic_ostream& operator<<( short value ); basic_ostream& operator<<( unsigned short value ); | (1) | |
basic_ostream& operator<<( int value ); basic_ostream& operator<<( unsigned int value ); | (2) | |
basic_ostream& operator<<( long value ); basic_ostream& operator<<( unsigned long value ); | (3) | |
basic_ostream& operator<<( long long value ); basic_ostream& operator<<( unsigned long long value ); | (4) | (since C++11) |
basic_ostream& operator<<( float value ); basic_ostream& operator<<( double value ); basic_ostream& operator<<( long double value ); | (5) | |
basic_ostream& operator<<( bool value ); | (6) | |
basic_ostream& operator<<( const void* value ); | (7) | |
basic_ostream& operator<<( std::nullptr_t ); | (8) | (since C++17) |
basic_ostream& operator<<( std::basic_streambuf<CharT, Traits>* sb); | (9) | |
basic_ostream& operator<<( std::ios_base& (*func)(std::ios_base&) ); | (10) | |
basic_ostream& operator<<( std::basic_ios<CharT,Traits>& (*func)(std::basic_ios<CharT,Traits>&) ); | (11) | |
basic_ostream& operator<<( std::basic_ostream<CharT,Traits>& (*func)(std::basic_ostream<CharT,Traits>&) ); | (12) |
Inserts data into the stream.
value
is short
or int
, then casts it to unsigned short
or unsigned int
if ios_base::flags() & ios_base::basefield
is ios_base::oct
or ios_base::hex
. After that, casts to long
in any case and outputs as in (3). If value
is unsigned short
or unsigned int
, casts to unsigned long
and outputs as in (3).num_put::put()
. If the end of file condition was encountered during output (put().failed() == true
), sets ios::badbit
.*this << s
, where s
is a null-terminated character type string.sb
is a null pointer. If it is, executes setstate(badbit)
and exits. Otherwise, extracts characters from the input sequence controlled by sb
and inserts them into *this
until one of the following conditions are met: setstate(failbit)
. If an exception was thrown while extracting, sets failbit
and, if failbit
is set in exceptions()
, rethrows the exception.func(*this)
. These overloads are used to implement output I/O manipulators such as std::endl
.value | - | integer, floating-point, boolean, or pointer value to insert |
func | - | function to call |
sb | - | pointer to the streambuffer to read the data from |
*this
func(*this)
There are no overload for pointers to non-static member, pointers to volatile, or function pointers (other than the ones with signatures accepted by the (10-12) overloads). Attempting to output such objects invokes implicit conversion to bool
, and, for any non-null pointer value, the value 1
is printed (unless boolalpha
was set, in which case true
is printed).
Character and character string arguments (e.g., of type char
or const char*
) are handled by the non-member overloads of operator<<
. Attempting to output a character using the member function call syntax (e.g., std::cout.operator<<('c');
) will call one of overloads (2-4) and output the numerical value. Attempting to output a character string using the member function call syntax will call overload (7) and print the pointer value instead.
#include <iostream> #include <iomanip> #include <sstream> int main() { std::istringstream input(" \"Some text.\" "); volatile int n = 42; double f = 3.14; bool b = true; std::cout << n // int overload << ' ' // non-member overload << std::boolalpha << b // bool overload << " " // non-member overload << std::fixed << f // double overload << input.rdbuf() // streambuf overload << &n // bool overload: volatile int* doesn't convert to const void* << std::endl; // function overload }
Output:
42 true 3.140000 "Some text." true
inserts character data (function template) |
|
performs stream I/O of strings (function template) |
|
performs stream input and output of bitsets (function) |
|
serializes and deserializes a complex number (function template) |
|
performs stream input and output on pseudo-random number engine (function template) |
|
performs stream input and output on pseudo-random number distribution (function template) |
|
inserts a character (public member function) |
|
inserts blocks of characters (public member function) |
|
(C++17) | converts an integer or floating-point value to a character sequence (function) |
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