In this section, we will cover the basic syntax rules of COBOL, which are essential for writing and understanding COBOL programs. COBOL (Common Business-Oriented Language) has a unique syntax that is designed to be readable and easy to understand, even for those who are not programmers.

1. Divisions: COBOL programs are divided into four main divisions:

   • IDENTIFICATION DIVISION: Contains metadata about the program.
   • ENVIRONMENT DIVISION: Specifies the environment in which the program will run.
   • DATA DIVISION: Defines the variables and data structures used in the program.
   • PROCEDURE DIVISION: Contains the executable instructions of the program.

2. Sections and Paragraphs: Divisions are further divided into sections, and sections can contain paragraphs. Paragraphs are the smallest units of code in COBOL.

3. Sentences and Statements: A sentence in COBOL is a series of one or more statements ending with a period. Statements are the individual instructions in the program.

4. Columns and Formatting: COBOL has specific column requirements:

   • Columns 1-6: Sequence numbers (optional).
   • Column 7: Indicator area (e.g., '*' for comments).
   • Columns 8-11: Area A (for division, section, and paragraph names).
   • Columns 12-72: Area B (for statements and code).
   • Columns 73-80: Identification area (optional, often used for version control).

Here is a simple example of a COBOL program to illustrate the basic structure and syntax:

• IDENTIFICATION DIVISION: This division contains the PROGRAM-ID which uniquely identifies the program. In this case, the program is named HelloWorld.
• ENVIRONMENT DIVISION: This division is used to specify the environment in which the program will run. It is empty in this simple example.
• DATA DIVISION: This division is used to define variables and data structures. It is also empty in this example.
• PROCEDURE DIVISION: This division contains the executable code. The DISPLAY statement outputs the text 'Hello, World!' to the screen, and the STOP RUN statement ends the program.

Let's look at a more detailed example that includes variables and arithmetic operations:

• WORKING-STORAGE SECTION: This section in the DATA DIVISION is used to declare variables. NUM1 and NUM2 are defined with a picture clause (PIC) indicating they are two-digit numbers. RESULT is a three-digit number.
• ADD Statement: The ADD statement adds NUM1 and NUM2 and stores the result in RESULT.
• DISPLAY Statement: This statement outputs the result to the screen.

Write a COBOL program that displays your name on the screen.

Solution:

Write a COBOL program that subtracts two numbers and displays the result.

Solution:

• Column Formatting: Ensure that you follow the column formatting rules strictly. Misplacing code outside the designated columns can lead to syntax errors.
• Periods: Every sentence in COBOL must end with a period. Missing periods can cause unexpected behavior or errors.
• Case Sensitivity: COBOL is not case-sensitive, but it is a good practice to follow a consistent style (e.g., using uppercase for keywords).

In this section, we covered the basic syntax rules of COBOL, including the structure of a COBOL program, key concepts, and practical examples. Understanding these fundamentals is crucial for writing and reading COBOL programs effectively. In the next section, we will delve into the various data types available in COBOL.