Data is persistent when it survives after the program is finished.
A file is a collection of data that is located on persistent storage, such as a hard drive, a CD-ROM, or other storage device.
Files store data in either text or binary format.
You should include the fstream standard library when your program reads from, or writes to, files.
The fstream object may be used both for file input and file output.
You can open a file with either the open member function or a constructor.
The purpose of opening a file is to establish a path of communication between the file and a file stream object in your program.
The purpose of closing a file is to free system resources that are required to maintain the path of communication between the file and the file stream object in your program.
A constructor is a function that is automatically called when you attempt to create an instance of an object.
The fail member function is a better choice than the eof member function for detecting end of file in a text file.
File stream objects should be passed as function arguments by reference rather than by value.