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COBOL Tutorial

What is COBOL?

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Definition and Purpose of COBOL

COBOL (Common Business-Oriented Language) is a high-level programming language designed specifically for business data processing needs. First introduced in 1959, COBOL has been one of the most enduring programming languages in history, with billions of lines of COBOL code still in active use today.

COBOL was created to provide a programming language that could:

  • Be used across different computing systems
  • Process large volumes of business data efficiently
  • Create human-readable programs accessible to non-technical users
  • Handle complex business rules and calculations
  • Support file and record processing for business data

COBOL was revolutionary for its time because it used English-like syntax rather than mathematical notation, making it more accessible to business analysts and non-mathematician programmers. This design choice aligned with its purpose: to create a standardized way for businesses to develop data processing applications.

cobol
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IDENTIFICATION DIVISION. PROGRAM-ID. HELLO-WORLD. PROCEDURE DIVISION. DISPLAY "Hello, business world!". STOP RUN.

The simple example above demonstrates COBOL's English-like structure, with clear divisions and statements that resemble natural language sentences.

History and Evolution of COBOL

COBOL's development was spearheaded by Grace Hopper, often referred to as the "mother of COBOL," along with a committee of industry professionals.

COBOL-60 (1959)

Original language specification that established the foundation for all future versions.

COBOL-68/74 (1968-1974)

Standardized by ANSI, adding improved data handling and introducing structured programming with nested IF statements.

COBOL-85 (1985)

Major enhancement adding scope terminators (END-IF, END-PERFORM), inline PERFORM statements, and additional control structures.

COBOL 2002/2014 (2002-2014)

Modern versions adding object-oriented programming, XML processing, cultural adaptability, and free-form syntax.

The language has continually evolved while maintaining backward compatibility, allowing systems designed decades ago to still run today with minimal changes.

Role of COBOL in Business Computing

COBOL's influence on business computing cannot be overstated:

Financial Sector

95% of ATM transactions run through COBOL systems, with approximately 43% of banking systems built on COBOL.

Insurance

More than 60% of insurance business runs on COBOL, handling policy management, claims processing, and reporting.

Government Systems

Critical infrastructure including Social Security, IRS, Medicare/Medicaid all rely on COBOL for their core processing.

Retail

Many point-of-sale systems, inventory management, and supply chain applications use COBOL backends.

Relationship Between COBOL and Operating Systems

COBOL programs typically run on mainframe environments, though they can be compiled and executed on various platforms:

Mainframe Platforms

  • z/OS and OS/390: IBM's mainframe operating systems where most enterprise COBOL runs
  • JCL (Job Control Language) mediates the relationship between COBOL programs and the OS
  • Mainframe COBOL often interfaces with CICS, IMS, DB2, and other mainframe subsystems

Distributed Platforms

  • UNIX/Linux: Supported by multiple COBOL compilers including Micro Focus and GnuCOBOL
  • Windows: Modern COBOL development environments like Visual COBOL available
  • Cloud platforms: Containerized COBOL applications exist in modern cloud environments

The relationship between COBOL and the operating system often involves runtime libraries that provide system services to COBOL programs, allowing the same business logic to run on different platforms.

Why COBOL is Still Relevant Today

Despite being more than 60 years old, COBOL remains critical for several reasons:

Reliability

COBOL systems often achieve 99.999% uptime, critical for financial and government systems.

Massive Code Base

220+ billion lines of COBOL in production, representing enormous investment and proven solutions.

Critical Systems

Powers 90% of global financial transactions, making it essential infrastructure.

Business Logic

Encapsulates decades of verified business rules that would be risky to rewrite.

The COVID-19 pandemic highlighted COBOL's continued relevance when many state unemployment systems, built on COBOL, needed urgent updates to handle unprecedented claim volumes. This led to a renewed interest in COBOL skills.

Modern enhancements have kept COBOL relevant, including integration with web services, XML/JSON processing, and continued compiler improvements.

Practical COBOL Example

Here's a slightly more advanced COBOL example that demonstrates a simple payroll calculation:

cobol
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IDENTIFICATION DIVISION. PROGRAM-ID. PAYROLL-CALC. ENVIRONMENT DIVISION. DATA DIVISION. WORKING-STORAGE SECTION. 01 EMPLOYEE-WAGE PIC 9(5)V99. 01 HOURS-WORKED PIC 9(3)V99. 01 WEEKLY-PAY PIC 9(6)V99. PROCEDURE DIVISION. MOVE 15.50 TO EMPLOYEE-WAGE. MOVE 40.00 TO HOURS-WORKED. COMPUTE WEEKLY-PAY = EMPLOYEE-WAGE * HOURS-WORKED. DISPLAY "Weekly Pay: $" WEEKLY-PAY. STOP RUN.

This COBOL program demonstrates some key language features: the four divisions, data declarations with PICTURE clauses, and computation operations.

Exercise: Identify COBOL Structure

Looking at the payroll example above, identify the following:

  1. List all four divisions in a COBOL program
  2. What is the purpose of the WORKING-STORAGE SECTION?
  3. What do the numbers 9(5)V99 mean in the PICTURE clause?
  4. What does the COMPUTE statement do?
  5. Why is STOP RUN included at the end?

FAQ

Is COBOL a dead language?

No, COBOL is not dead. Despite being over 60 years old, COBOL continues to run critical systems in banking, insurance, government, and many other sectors. An estimated 220+ billion lines of COBOL code are still in active use, processing millions of transactions daily.

Why do businesses still use COBOL instead of modern languages?

Businesses continue using COBOL due to its reliability, the enormous risk of replacing core systems, decades of validated business logic, performance for data processing tasks, and decimal precision critical for financial calculations.

Is it worth learning COBOL today?

Learning COBOL can be valuable due to the growing skills gap as experienced programmers retire, creating job opportunities with competitive salaries. COBOL skills are often combined with modern technology expertise to help organizations modernize gradually.