# 15.2. Streams¶

To get input from a file or send output to a file, you have to create an ifstream object (for input files) or an ofstream object (for output files). These objects are defined in the header file fstream, which you have to include.

A stream is an abstract object that represents the flow of data from a source like the keyboard or a file to a destination like the screen or a file.

We have already worked with two streams: cin, which has type istream, and cout, which has type ostream. cin represents the flow of data from the keyboard to the program. Each time the program uses the >> operator or the getline function, it removes a piece of data from the input stream.

Similarly, when the program uses the << operator on an ostream, it adds a datum to the outgoing stream.