Handling Computer Files

Handling Computer Files - SSS Two Computer Studies

TOPIC: Handling Computer Files

CLASS: SSS Two

Basic File Operations

Following are some of the basic operations that can be performed on computer files:

Create: To make a new, empty file or initiate a new document.
Delete: To remove a file from a storage location (permanently or to the Recycle Bin/Trash).
Retrieve: To find and access an existing file from storage.
Copy: To create an identical duplicate of a file in a different location, leaving the original intact.
View: To display the contents of a file without necessarily editing it.
Update/Edit: To modify the contents of a file or to change its attributes (e.g., read-only, hidden).
Open: To access a file for reading or writing, or to launch its associated application.
Close: To exit the application or program used to access the file, typically saving any changes made.
Rename: To change the name of a file.
Move: To relocate a file from one location to another on the same or a different storage device, deleting it from the original location.
Share: To grant access to a file to other users (e.g., through email, cloud storage, or network sharing).
Compress/Archive: To reduce the file size by compressing its data (e.g., creating ZIP or RAR files) for easier storage or transfer.
Encrypt/Decrypt: To secure file data by converting it into an unreadable format (encrypt) and then restoring it to its original, readable form (decrypt).

Sequential File Creation

There are many ways to organize data in a file system. One common way is by using BASIC Programming Language:

Steps involved in Creating a Sequential File Using BASIC:

Choose a DOS file name: A DOS file name is a string consisting of a base name (at most eight characters) followed by an optional extension (a period and at most three characters). Blank spaces are not allowed. Examples: INCOME.86, CUSTOMER.DAT, FORT500. (Note: Modern operating systems support longer file names and more characters, but this applies to traditional DOS compatibility.)
Choose a number (1-255) as the file reference number: While the file is being used by the program, it will be identified by this unique number.
Execute the OPEN statement: Use the statement OPEN "filename" FOR OUTPUT AS #n where n is the chosen reference number. This prepares the file for writing.
Place data into the file with the WRITE statement: Use WRITE #n, data_item1, data_item2, ... to write data. The WRITE statement automatically adds commas between items and quotation marks around string data in the file.
Execute CLOSE #n: After all data has been recorded in the file, execute CLOSE #n to properly save and close the file.

Example 1: A program to demonstrate the use of the WRITE statement.


10 REM Demonstrate use of WRITE statement
20 CLS
30 OPEN "DEMO.TXT" FOR OUTPUT AS #1  Open a file for writing
40 WRITE #1, "ENIAC"
50 WRITE #1, 1946
60 WRITE #1, "ENIAC", 1946
70 LET A$ = "Eckert"
80 LET B$ = "Mauchly"
90 WRITE #1, 14 * 139, "J.P. ", A$, B$, "John"
100 CLOSE #1  Close the file
110 END

[run] File Content of DEMO.TXT (if viewed in a text editor):


"ENIAC"
1946
"ENIAC",1946
1946,"J.P. ","Eckert","Mauchly","John"

Example 2: Write a program to create a file EXAMFILE.DAT with student names and marks in English and Mathematics.


10 REM A program to create a file EXAMFILE.DAT and record data into it
20 OPEN "EXAMFILE.DAT" FOR OUTPUT AS #1
30 READ Names$, Maths, Eng 
40 DO WHILE Names$ <> "EOD"  
50    WRITE #1, Names$, Maths, Eng  
60    READ Names$, Maths, Eng  
70 LOOP
80 CLOSE #1
90 DATA Joy, 87, 75
100 DATA Gbenda, 88, 67
110 DATA Viola, 77, 70  
120 DATA EOD, 0, 0  
130 END

[run] Action: This program creates a file named "EXAMFILE.DAT".
[run] Content of EXAMFILE.DAT (if viewed in a text editor):


"Joy",87,75
"Gbenda",88,67
"Viola",77,70

Accessing a Sequential File

Data stored in a sequential file can be accessed and read in order using the following steps:

Choose a number (1-255) to be the reference number for the file.
Execute the OPEN statement: OPEN "filename" FOR INPUT AS #n, where n is the reference number. This prepares the file for reading.
Read data from the file using the INPUT #n statement (e.g., INPUT #n, variable1, variable2). This reads values sequentially from the file.
After the desired items have been found or the end of the file is reached, close the file with the statement CLOSE #n. The EOF(n) function can be used to check for the End Of File.

Example 3: Write a program to display the contents of EXAMFILE.DAT (created in Example 2).


10 REM Read data from EXAMFILE.DAT file and display it
20 OPEN "EXAMFILE.DAT" FOR INPUT AS #1
30 PRINT "Name", "Maths", "English"  Corrected: English with quotes
40 PRINT "----------------------------"
50 DO WHILE NOT EOF(1)  Loop while not at the End Of File (1)
60    INPUT #1, Names$, Maths, Eng  Corrected: INPUT #1 for reading from file
70    PRINT Names$, Maths, Eng
80 LOOP
90 CLOSE #1
100 END

[run] Output:


Name           Maths          English
----------------------------
Joy            87             75
Gbenda         88             67
Viola          77             70

File Insecurity

File security is a featur e of a file system that controls which users can access which files, and places limitations on what users can do to them. If these measures are not put in place, files will be insecure, leading to potential risks.

Effects of File Insecurity

File insecurity can have several detrimental consequences, including:

Data Loss: Unauthorized access or accidental deletion can lead to the permanent loss of critical files.
Data Corruption: Malicious activities (like viruses or malware) or software glitches can compromise the integrity of files, rendering them unusable or inaccurate.
Data Unreliability: Insecure files may be altered or tampered with without authorization, compromising their accuracy and trustworthiness.
System Disruptions: File-related security issues can disrupt normal system operations, leading to slowdowns, crashes, or even system instability.
Security Vulnerabilities: Insecure files can expose sensitive or confidential information to unauthorized individuals, creating significant privacy and security risks.

File Security Methods

To protect computer files from unauthorized access, damage, or loss, various security methods can be employed:

Use of Backups: This involves making copies of data so that these additional copies can be used to restore the original files after a loss event (e.g., hardware failure, accidental deletion). Backups can be stored on removable media like external hard drives, USB drives, or cloud storage.
Use of Antivirus Software: An antivirus is software designed to detect, prevent, and remove malicious software (like viruses, worms, and Trojans) that can corrupt or compromise files.
Use of Passwords: A password is a string of characters used for authenticating a user. Passwords prevent unauthorized access to computer systems, accounts, files, or parts of files by requiring a user to enter a secret code.
Proper Labeling of Storage Devices: Labeling storage devices (like USB drives, external hard drives, CDs/DVDs) clearly helps you identify whats stored on them, reducing the risk of accidental deletion or formatting.
File Management: Good file management involves organizing folders, documents, and multimedia into logical categories and subcategories. This helps prevent files from being misplaced or unnecessarily deleted.
Two-Factor Authentication (2FA): This adds an extra layer of security by requiring a second form of verification in addition to your password (e.g., a code sent to your phone).
Access Control Lists (ACLs): These define specific permissions for individual users or groups, such as read-only access, read/write access, or execute permissions, limiting what users can do with a file.
File Encryption: This method encodes files so they are unreadable without the correct decryption key, making the data unintelligible to unauthorized individuals.
Firewalls: Firewalls are security systems that monitor and control incoming and outgoing network traffic. They block unauthorized network access to your computer or network, helping to prevent malware from entering.
Security Awareness Training: Educating users about security best practices, such as recognizing phishing emails, avoiding suspicious links, and reporting security incidents, is crucial for preventing human-error related breaches.

Differences Between Computer Files and Manual Files

Computer File	Manual File
Transferred electronically (e.g., via network, USB, email).	Transported through physical means (e.g., by hand, mail).
Difficult to destroy permanently without specific actions; can last for a long time on digital media.	Can wear out, degrade, or be depleted easily by physical handling or environmental factors.
Requires specialized hardware (computer) and software (operating system, application) for access and manipulation.	Generally easier to access directly (e.g., by opening a drawer or folder) without specialized equipment.
Capable of storing vast amounts of information in a compact digital space.	Limited storage capacity compared to computers; requires significant physical space for large volumes of data.
Susceptible to cyber threats (e.g., hacking, malware, viruses).	Susceptible to physical threats (e.g., theft, fire, water damage, natural disasters).
Environmentally friendly in terms of less paper consumption.	Can contribute to deforestation due to paper consumption and waste.
Searching and sorting large volumes of data is extremely fast.	Searching and sorting large volumes of data can be very time-consuming and tedious.
Easy to backup, replicate, and store in multiple locations.	Difficult and time-consuming to create multiple physical copies.

Advantages of Computerized Files

Using computerized files offers numerous benefits compared to manual file systems:

Computers can perform calculations and data processing quickly and efficiently.
Data can be retrieved quickly and easily using search functions.
Documents that are lost or corrupted can often be retrieved from backups.
Security can be robust with proper measures (passwords, encryption), making it hard to break into.
Computerized systems generally make work easier by automating tasks.
Its quicker to find and sort information, saving time and effort.
Transactions and data handling can be managed more properly and accurately by computers than manually.
Reduces physical storage space requirements.
Facilitates easy sharing and collaboration on documents.

Limitations of Computerized Files

Despite their many advantages, computerized file systems also have some limitations:

High Costs: Setting up and maintaining a computerized system can be expensive due to initial hardware, software licenses, infrastructure, and ongoing maintenance costs.
Technological Vulnerabilities: Computerized systems are susceptible to various issues such as hardware failures, software glitches, power outages, and internet disruptions, which can make data inaccessible.
Security Risks: Files are always at risk from cyberattacks, unauthorized access, data breaches, and malicious software.
Data Dependency: An over-reliance on computerized systems can create significant vulnerabilities if the system fails, data is lost, or the necessary technical skills are unavailable.
Steep Learning Curve: Users and IT personnel often require training and ongoing learning to effectively use, maintain, and secure complex computerized systems.
Environmental Impact: The production, use, and disposal of electronic equipment contribute to e-waste and consume significant energy.

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