Lesson 2

Using EVALUATE for Conditional Logic

Transitioning to EVALUATE Statements

Welcome back! In this lesson, we'll explore another powerful tool for decision-making: the EVALUATE statement. Similar to a switch-case structure in other languages, EVALUATE helps manage complex decision paths effectively.

What You'll Learn

In this lesson, you'll learn how to use the EVALUATE statement for conditional logic in COBOL. We'll discuss its syntax and show you how it can be employed to make your code more readable and maintainable. Here's a sneak peek at what we'll cover:

cobol
1IDENTIFICATION DIVISION. 2PROGRAM-ID. EvaluateDemo. 3DATA DIVISION. 4WORKING-STORAGE SECTION. 501 Account-Type PIC X(1). 601 Account-Description PIC X(20). 7PROCEDURE DIVISION. 8 MOVE 'S' TO Account-Type. 9 EVALUATE Account-Type 10 WHEN 'S' 11 MOVE "Savings Account" TO Account-Description 12 WHEN 'C' 13 MOVE "Checking Account" TO Account-Description 14 WHEN OTHER 15 MOVE "Unknown Account" TO Account-Description 16 END-EVALUATE. 17 DISPLAY "Account Type: " Account-Type. 18 DISPLAY "Description: " Account-Description. 19 STOP RUN.

This example demonstrates how different account types (e.g., Savings, Checking) can be identified and described using EVALUATE.

Understanding the EVALUATE Statement

The EVALUATE statement is a powerful tool in COBOL that allows you to evaluate a given expression against multiple conditions. It provides a structured way to handle complex decision-making scenarios without resorting to deeply nested IF statements. In the example above, we used EVALUATE to determine the description of an account based on its type, simplifying the conditional logic. We first check if the account type is 'S' (Savings), 'C' (Checking), or any other value, and assign the corresponding description to the Account-Description variable. With EVALUATE, you can handle multiple conditions in a more readable and efficient manner.

Why It Matters

Understanding how to use the EVALUATE statement is crucial for several reasons:

  1. Enhanced Readability: By using EVALUATE, you can simplify complex decision-making processes, making your code easier to read and maintain.

  2. Efficient Decision-Making: With EVALUATE, you can handle multiple conditions in a more structured manner, which helps avoid deeply nested IF statements.

  3. Scalability: As your applications grow more complex, using EVALUATE statements can make your conditional logic more scalable and easier to expand.

Imagine you’re constructing a banking application that needs to process various types of accounts. With EVALUATE, you can easily extend your logic to handle new account types as they arise without making your codebase messy.

Excited to master another powerful tool in COBOL? Let's dive in and see how EVALUATE can make your programming experience smoother and more efficient. Let's start the practice section together!

Enjoy this lesson? Now it's time to practice with Cosmo!

Practice is how you turn knowledge into actual skills.