10. DATA FILES

Many applications require that information be written to or read from an auxiliary device.Such information is stored on the memory device in the form of a data file. Thus data files allow us to store information permanently, and to access and alter information whenever necessary.

There are two different types of data files, called stream-oriented (or standard access) data files, and system-oriented (or low-level) data files.Stream oriented data files are generally easier to work with and are therefore commonly used.

Stream-oriented data files van be subdivided into  two categories - they are text files and unformatted data files.Text files consist of consecutive characters.These characters can be interpreted as individual data items, or as components of strings or numbers.Unformatted data files organizes data into blocks containing contiguous bytes of information.These blocks represent more complex data structures, such as arrays and structures.


System-oriented data files are more closely related to the computer's memory system than stream oriented data files. They are more complicated to work with, though their use may be more efficient for certain kinds of applications.

Data files are most frequently used to store user's data. However data related to numbers can be efficiently stored in binary files, which are also useful to hanle file containing machine language contents e.g. exe or .com files.The files which are stored in binary format differ significantly from data (also called as text) files.

In this chapter we are only concerned with stream oriented-data files.