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COBOL Tutorial

COBOL METHOD-ID - Quick Reference

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Overview

The METHOD-ID statement in object-oriented COBOL defines a method within a class or interface. It specifies the method name, parameters, and implementation, allowing objects to perform specific operations.

Purpose and Usage

  • Define object behavior through methods
  • Encapsulate functionality within classes
  • Support object-oriented programming concepts
  • Enable method invocation on objects

Syntax

The METHOD-ID statement follows a specific structure:

Basic Syntax

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METHOD-ID. method-name.
    DATA DIVISION.
    LINKAGE SECTION.
        01  parameter1 PIC X(10).
        01  parameter2 PIC 9(5).
    PROCEDURE DIVISION USING parameter1, parameter2.
        * Method implementation
        EXIT METHOD.
END METHOD method-name.

Methods can have parameters and return values.

Example: Simple Method

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METHOD-ID. GetName.
    DATA DIVISION.
    LINKAGE SECTION.
        01  return-name PIC X(30).
    PROCEDURE DIVISION RETURNING return-name.
        MOVE employee-name TO return-name
        EXIT METHOD.
END METHOD GetName.

Example: Method with Parameters

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METHOD-ID. CalculateSalary.
    DATA DIVISION.
    LINKAGE SECTION.
        01  hours-worked PIC 9(3).
        01  hourly-rate PIC 9(3)V99.
        01  total-salary PIC 9(6)V99.
    PROCEDURE DIVISION USING hours-worked, hourly-rate RETURNING total-salary.
        COMPUTE total-salary = hours-worked * hourly-rate
        EXIT METHOD.
END METHOD CalculateSalary.

Practical Examples

Here are some practical uses of METHOD-ID in object-oriented COBOL:

Employee Class Methods

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CLASS-ID. Employee.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
OBJECT-COMPUTER.
DATA DIVISION.
WORKING-STORAGE SECTION.
    01  employee-name PIC X(30).
    01  employee-id PIC 9(6).
    01  employee-salary PIC 9(7)V99.
PROCEDURE DIVISION.
METHOD-ID. SetName.
    DATA DIVISION.
    LINKAGE SECTION.
        01  new-name PIC X(30).
    PROCEDURE DIVISION USING new-name.
        MOVE new-name TO employee-name
        EXIT METHOD.
END METHOD SetName.
 
METHOD-ID. GetSalary.
    DATA DIVISION.
    LINKAGE SECTION.
        01  return-salary PIC 9(7)V99.
    PROCEDURE DIVISION RETURNING return-salary.
        MOVE employee-salary TO return-salary
        EXIT METHOD.
END METHOD GetSalary.
END CLASS Employee.

Methods for getting and setting employee data.

Calculator Methods

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METHOD-ID. Add.
    DATA DIVISION.
    LINKAGE SECTION.
        01  a PIC 9(5).
        01  b PIC 9(5).
        01  result PIC 9(6).
    PROCEDURE DIVISION USING a, b RETURNING result.
        COMPUTE result = a + b
        EXIT METHOD.
END METHOD Add.
 
METHOD-ID. Multiply.
    DATA DIVISION.
    LINKAGE SECTION.
        01  a PIC 9(5).
        01  b PIC 9(5).
        01  result PIC 9(10).
    PROCEDURE DIVISION USING a, b RETURNING result.
        COMPUTE result = a * b
        EXIT METHOD.
END METHOD Multiply.

Mathematical operation methods.

Best Practices

  • Use descriptive method names that clearly indicate their purpose.
  • Keep methods focused on a single responsibility.
  • Use appropriate parameter types and sizes.
  • Always use EXIT METHOD to properly end method execution.
  • Document method parameters and return values.

Common Pitfalls

  • Forgetting to use EXIT METHOD to end method execution.
  • Not properly defining parameter types in LINKAGE SECTION.
  • Using methods outside of class or interface definitions.
  • Mixing procedural and object-oriented concepts incorrectly.

Test Your Knowledge

1. What is the primary purpose of the METHOD-ID statement in COBOL?

  • To define a program ID
  • To define a method within a class or interface
  • To identify a file
  • To declare a variable

2. In which type of COBOL is METHOD-ID used?

  • Standard COBOL
  • Object-oriented COBOL
  • Procedural COBOL
  • Legacy COBOL

3. What sections can a METHOD-ID contain?

  • Only PROCEDURE DIVISION
  • DATA DIVISION and PROCEDURE DIVISION
  • ENVIRONMENT DIVISION, DATA DIVISION, and PROCEDURE DIVISION
  • All four divisions

4. How do you pass parameters to a method?

  • Using the USING clause
  • Using global variables
  • Using the WITH clause
  • Using the PASS clause

5. What is the difference between a method and a paragraph?

  • They are the same
  • Methods belong to classes, paragraphs belong to programs
  • Methods are faster
  • Paragraphs are obsolete

Frequently Asked Questions

Related Concepts

CLASS Statement

Defining classes in object-oriented COBOL.

INTERFACE Statement

Defining interfaces in COBOL.

INVOKE Statement

Invoking methods on objects.

Object-Oriented COBOL

Overview of OO COBOL concepts.

Encapsulation

Understanding encapsulation in COBOL.

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