Day 3: Learning COBOL Syntax and Understanding Basic Data Types for Writing Efficient Business Programs


 

1. Introduction: COBOL’s Human-Readable Design

COBOL stands apart from most programming languages because of its English-like syntax. It was intentionally designed to be readable and understandable by people in business, not just programmers. Every COBOL statement ends with a period (.) and often reads like a plain English sentence. This approach made it revolutionary for its time and still contributes to its maintainability today.

For instance, a COBOL instruction like

DISPLAY "HELLO WORLD".

is easy to understand without prior programming experience. COBOL’s syntax encourages clarity, structure, and documentation — key principles in large business systems.

2. Variables and Basic Data Types in COBOL

In COBOL, all variables are defined inside the DATA DIVISION, particularly under the WORKING-STORAGE SECTION. Each variable has a level number and a PICTURE (PIC) clause that describes its data type and format.

Here are a few common examples:

  • PIC X(n): Represents an alphanumeric (string) value of length n.

  • PIC 9(n): Represents a numeric value with n digits.

  • PIC A(n): Represents alphabetic characters only.

For example:

01 STUDENT-NAME PIC X(30).
01 STUDENT-AGE  PIC 99.

This structure gives COBOL precise control over data layout — a critical advantage when handling financial or record-based systems.

3. The Power of Structured Data Representation

COBOL’s data representation is hierarchical. You can group related fields using levels like 01, 05, and 10, creating complex record structures that mirror real-world data. This makes COBOL ideal for business logic, where clarity and structure are paramount.

Example:

01 EMPLOYEE-DETAILS.
   05 EMP-NAME  PIC X(25).
   05 EMP-ID    PIC 9(5).
   05 EMP-SALARY PIC 9(7)V99.

This structured layout makes COBOL programs behave like well-organized databases, reflecting business entities directly in code.

🧠 Key Takeaways

  • COBOL syntax is English-like, structured, and easy to read.

  • Variables are declared in the DATA DIVISION with PIC clauses defining type and size.

  • COBOL’s hierarchical data representation makes it excellent for business data modeling.

💻 Practice Task

  1. Create a new COBOL file called DataTypesDemo.cbl.

  2. Write a simple program that declares and displays variables for a student’s name, age, and grade:

IDENTIFICATION DIVISION.
PROGRAM-ID. DATATYPES-DEMO.

DATA DIVISION.
WORKING-STORAGE SECTION.
01 STUDENT-NAME  PIC X(20) VALUE "PRAVEEN".
01 STUDENT-AGE   PIC 99 VALUE 21.
01 STUDENT-GRADE PIC A VALUE "A".

PROCEDURE DIVISION.
    DISPLAY "STUDENT DETAILS:".
    DISPLAY "NAME: " STUDENT-NAME.
    DISPLAY "AGE: " STUDENT-AGE.
    DISPLAY "GRADE: " STUDENT-GRADE.
    STOP RUN.

  1. Save the file — we’ll build on this program tomorrow to include user input and arithmetic operations.

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