PPT Slide
- A file is an external source from which data may be obtained or an external destination to which it may be sent. Data can not be transferred to or from a file until the file is connected to the program.
A connection between a unit and a file has certain connection properties. When a unit becomes connected to a file by execution of an open statement, the following properties may be established:
1) An access method, sequential or direct, is always established.
2) A form, formatted or unformatted, is always established.
3) An initial position, rewind or append, specifies initial positioning of the file during execution of open statement
4) A permanence property, temporary or permanent, specifies disposition of the file when the connection is terminated.
5) An action property, read, write or read-write, specifies which kinds of