std::basic_ostream::operator<<
| 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 ); |
(5) | |
| basic_ostream& operator<<( bool value ); |
(6) | |
| basic_ostream& operator<<( const void* value ); |
(7) | |
| basic_ostream& operator<<( std::basic_streambuf<CharT, Traits>* sb); |
(8) | |
| basic_ostream& operator<<( basic_ostream& st, std::ios_base& (*func)(std::ios_base&) ); |
(9) | |
Inserts data into the stream.
The (1-7) versions of the operator behave as formatted output functions, and the 8) version behaves as unformatted output function. These functions begin execution by constructing an object of type sentry, which flushes the tie()'d output buffers if necessary and checks the stream errors. After construction, if the sentry object returns false, the functions return without attempting any output. If an error occurs during output, formatted output functions set setstate(ios_base::failbit). If an exception is thrown during output, then ios::badbit is set (the exception is suppressed unless (exceptions()&badbit) != 0, in which case it is rethrown)
1-2) If 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)
3-4) Inserts an integer value by calling num_put::put()
5) Inserts a floating point value by calling num_put::put()
6) Inserts bool value by calling num_put::put()
7) Inserts a generic pointer value by calling num_put::put()
8) Inserts all data from sb. After constructing the sentry object, checks if 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:
- end-of-file occurs on the input sequence;
- inserting in the output sequence fails (in which case the character to be inserted is not extracted);
- an exception occurs (in which case the exception is caught).
If no characters were inserted, executes {{c|setstate(badbit)}. If an exception was thrown while extracting, sets failbit
9) Calls func(*this);. This overload is used to implement output I/O manipulators such as std::endl.
Contents |
[edit] Parameters
| value | - | integer, floating-point, boolean, or pointer value to insert |
| func | - | function to call |
| sb | - | pointer to the streambuffer to read the data from |
[edit] Return value
*this
[edit] Notes
There are no overload for pointers to volatile or function pointers (other than the ones with signatures accepted by the 9) overload). 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).
[edit] Example
#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 << std::endl; // function overload }
Output:
42 true 3.140000 "Some text." true
[edit] See also
| inserts character data (function) | |
| 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) | |
| performs stream input and output on pseudo-random number distribution (function) | |
| inserts a character (public member function) | |
| inserts blocks of characters (public member function) | |
