COBOL, which stands for Common Business Oriented Language, is one of the oldest high-level programming languages designed for business data processing. It was developed in the late 1950s and early 1960s, primarily by a committee of computer scientists and industry experts. The original specifications were established in 1959, and COBOL was first implemented in 1960.
Introduction
1. Historical Context
During the late 1950s, there was a pressing need for a standardized programming language that could handle business data processing tasks effectively. At that time, different computer manufacturers had their own proprietary languages, making it difficult to share and exchange programs across different systems. COBOL emerged as a solution to this problem, aiming for portability and ease of use.
2. Advantages and Relevance
COBOL was designed to be a self-documenting, English-like language, making it accessible to non-technical staff and easier to understand for business users. It gained widespread acceptance and became the dominant language for business applications. Even today, despite its age, COBOL continues to be in use and remains an integral part of many legacy systems.
3. Importance of COBOL
COBOL’s importance stems from its historical significance and the vast number of mission-critical applications that were initially written in COBOL. Many essential business systems still rely on COBOL, and its longevity can be attributed to the stability and reliability it offers.
Features and Structure of COBOL
| Division | Key Features |
|---|---|
| Data Division | – Data Types (Numeric, Alphabetic, Alphanumeric) |
| – Level Numbers for hierarchy | |
| – Picture Clause for data format | |
| – Occurs Clause for handling arrays | |
| Procedure Division | – Statements for program logic |
| – Paragraphs and Sections for organization | |
| – Conditional Statements (IF, ELSE, EVALUATE) | |
| – Looping (PERFORM, EVALUATE) | |
| Identification Division | – Program ID for unique identification |
| – Author and Installation information | |
| – Date Written | |
| – Remarks (Optional comments and notes) | |
| Environment Division | – Configuration Section (Hardware and software info) |
| – Input-Output Section (File handling and device details) |
Basic COBOL Programming Concepts
1. Data Types and Data Items
- Numeric: Numeric data types include integers (COMP) and decimals (COMP-3). They are used for arithmetic operations and calculations.
- Alphanumeric: Alphanumeric data types (e.g., PIC X(n)) store a combination of alphabetic and numeric characters.
2. Data Records and Files
- Data Records: COBOL structures data in records, which can be further divided into fields (data items). Each field contains a specific type of data.
- Files: COBOL programs work with files, which can be input, output, or both. File handling involves reading from and writing to these files.
3. Conditional Statements
- IF-ELSE: The IF-ELSE statement allows conditional execution based on specified conditions.
- EVALUATE: EVALUATE is a versatile conditional statement, acting as a multi-way decision-making construct.
4. Looping and Iterations
- PERFORM: PERFORM is used for creating loops in COBOL programs. It can iterate a specific number of times or until a condition is met.
- Nested PERFORM: COBOL allows nesting PERFORM statements for complex looping requirements.
COBOL Data Manipulation
| Operation Type | COBOL Keyword | Description |
|---|---|---|
| Arithmetic Operations | ||
| Addition | ADD | Adds values of specified variables and stores the result |
| Subtraction | SUBTRACT | Subtracts values of specified variables and stores the result |
| Multiplication | MULTIPLY | Multiplies values of specified variables and stores the result |
| Division | DIVIDE | Divides values of specified variables and stores the result |
COBOL File Handling
1. File Definition
- FILE SECTION: This section defines the files that the program will use, specifying their organization and access modes.
- FD (File Description): Describes the file structure, including record length, key fields, and data types.
2. File Organizations
- Sequential: Records are accessed sequentially from start to end.
- Indexed: Records are accessed using an index or key value.
- Relative: Records are accessed based on their relative position within the file.
3. File Access Modes
- Input (I/O) Mode: File is opened for reading (input) data.
- Output (O) Mode: File is opened for writing (output) data.
- Input-Output (I-O) Mode: File is opened for both reading and writing.
4. File Operations
- OPEN: Opens the file for input, output, or input-output operations.
- CLOSE: Closes the file after processing.
- READ: Reads a record from the file.
- WRITE: Writes a record to the file.
- REWRITE: Replaces the current record in the file.
- DELETE: Removes the current record from the file.
COBOL Program Design and Structure
| Concept | Description |
|---|---|
| Program Division | The main structure of a COBOL program |
| – Contains Identification, Environment, Data, and Procedure Divisions | |
| Data Division | Defines the data used in the program |
| – Contains Data, File, Working-Storage, and Local Storage Sections | |
| Procedure Division | Contains the actual program logic and instructions |
| – Contains Statements, Paragraphs, and Sections | |
| Paragraphs and Sections | Blocks of code within the Procedure Division |
| – Enhances program organization and reusability | |
| Subprograms | Segments of code that perform specific tasks |
| – Can be external (CALLed) or internal (PERFORMed) | |
| Modularization | Organizes code into manageable and reusable units |
| – Enhances maintainability and code readability |
Conclusion
In conclusion, Common Business Oriented Language (COBOL) is a powerful and versatile programming language that is still widely used for business applications today. COBOL is likely to remain a popular language for business applications for many years to come.
FAQs
COBOL (Common Business Oriented Language) is a high-level programming language primarily used for business data processing. It is designed for readability and is extensively used in financial, government, and administrative applications.
Yes, COBOL is still relevant today. Many critical business systems and legacy applications are written in COBOL, and it continues to be a fundamental part of the IT infrastructure in various industries.
COBOL is widely used in business applications due to its ease of understanding, English-like syntax, and strong support for file handling and data processing, making it suitable for business-oriented tasks.
The learning curve for COBOL can vary based on a person’s programming background. It is generally considered to have a straightforward syntax and is often well-documented, making it approachable for beginners.
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