File is a body of stored data or information in an electronic form at. Almost all
information storedon computers is in the form of files. Files reside on mass
storag de: 1ces such as hard drives,
CD-ROMS. rnagnetic tape, and floppy disks. When the central processing unit
(CPU) of acomputer needs data from a file, or needs to write data to a file, it
temporarily stores the file in itsmain memory, or Random Access Memory
(RAM), whie it works on the data.
Information in computers is usually classified into two different types of files:
data files (thosccontaining data) and program files (those that manipulate
data). Within each o these categories, many different types of files exist that store various kinds of information.
Different computer operatiag systems have unique rules for the naming of files.
Windows 95(Win95) an 1 cisk operating systems (DOS), for instance, make use
of an extension attached to the end of each filename in order to indicate the
type of file, Extensions tegin with a period (.), and then have one o more letters. An example of a file extension used in
Win95 and DOS is.bak:, which indicates that the file is a backup file.

When saving a file, a user can give it any name within the rules of the
operating system. In addition, the name must be unique. Two files in the same
directory may not have the same name, but some operating systems allow the-
same name for one file to be placed in more than onelocation. These additional
names are called aliases.
 

Directory files contain information used to organize , other files into a hierarchical structure. In the Macintosh operating system, directory files are called folders. The topmost directory in any file system is the root directory. A directory contained within another directory is called asubdirectory.

 Directories containing one or more subdirectories are called parent directories. Directory files contain programs or commands that are executable by the computer. Executable files have a .exe suffix at the end of their names and are often called EXE (pronounced EX-ee) files. Text files contain characters represented by their ASCII (AmericanStandard Code for Information Interchange) codes.
 

These files are often called ASCII (pronounced ASK-ee) files. Files that contain words, sentences, and bodies of paragraphs arefrequently referred to as text files.

FILE PROCESSING OPERATIONS

A computer file is a block, of arbitrary information, or resource for information,which is available, to a computer program and is usually
on some kind of durablestorage. A file is durable in the sense that it available for programs to use afterthe current program has finished. Computer files can be considered as the modern counter p art of paper documents which traditionally were kept in offices' and libraries'files, which are the source of the term.The file processing operations deal, with the various activities which ar
performed onthe file. These operations are briefly described as shown below;

File creation:

 The process of bringing file into existence is called file creation.

Searching:

 Scarching is locating data in a file by reference to a special field of each record/data called the key. The key is a unique filed used to identify certain record in a file. If a record is to be inserted into a file, it must be given a
uniquekey value.

Retrieving/reading:

This involves reading an existing data from a form of storage or input medium.

Writing:

 Writing is the act of recording data onto some form of storage.

Deleting:

 Tiis means removing a record or item of data from a storage medium such as disk/tape.

File updating:

This is an act of changing values in one or more records of a file without changing the organization of the file. That is making the file modern by adding most recent data to the file.

Sorting:

 Sorting means rearranging data in either ascending or descending
order.It involves the arrangement of grouped data elements into a predetermined sequence to facilitate file processing.

Calculating:

The arithmetic or logical manipulation of data in a file is referredtoas calculation.

File querying/interrogating:

 This is retrieving specific data from a file according tothe set of retrieval criteria.

File merging:

 Combining multiple sets of data files or records to produce only oneset, usually in an ordered sequence is referred to as file merging.

Reporting:

Reporting is a file processing operation that deals with the production (printing) of report from the file in a specified format.

File display:

The contents of a data file can be displayed either on the computerscreen as soft copy or printed on the paper as hard copy:

File storage:

 When a file is created, it is stored in the appropriate storage medium such as disk, flash disk, tape, drum, etc.

Data Processing

Data Processing is the analysis and organization of data by the repeated use
of one or more computer programs. Data processing is used extensively in business, engineering, and science and to an increasing extent in nearly all are as in which computers are used. Businesses use data processing for such : tasks as payroll preparation, accounting, record, keeping, inventory control, sales analysis, and the processing of bank and credit card account statements. Can besearched, accessed, and modified, such as hank account records, and transaction processing. A database is a colection of common records that Data processing is diyided into two kinds of processin : database processing can be searched, accessed, and modified, such as tank account recorde school transcripts, and income tax data. In database processing, a computerized database is used as the central source of eference data for the computations. Transaction processing refers to interaction between two computers in which onecomputer initiates a transaction and ancther computer provides the first with thedata or computation required for that function.


Most modern data processing uses one or more databases at one or more central sites. Transaction processing is used to access and update the databases when users need to immediately view or add information; other data processing programs are used at regular intervals to provide summary report of activity and database status. Examples of systems that involve all of these functions are automated teller machines, credit sales terminals, and airline reservation systems.

 We will be talking next time on the topic Data Processing.