ostream& operator<<是什么意思

Ostream is a C++ standard library class that represents an output stream. It provides a way to send data to an output device, such as the console or a file. The ostream class is defined in the iostream header file and is part of the standard C++ library. It is used to output data to the standard output stream, which is usually the console. It can also be used to output data to other types of output streams, such as files or network sockets. Some of the important member functions of the ostream class are the insertion operator (<<), the flush() function, and the put() function. The insertion operator is used to insert data into the output stream, whereas the flush() function is used to flush the output buffer and ensure that all data is written to the output device. The put() function is used to write a single character to the output stream.