Welcome to another important unit in your COBOL journey! In this lesson, we are going to explore the significance of decision-making in programming using IF
statements. Just like in real life, where you evaluate conditions and make decisions (e.g., whether to bring an umbrella based on the weather), in programming, this skill is crucial for developing efficient and functional applications.
In this unit, you will learn how to use IF
statements in COBOL to make decisions based on conditions. We will cover basic decision-making scenarios and teach you how to create simple and compound conditional statements. Here is a snippet of what you'll be able to understand by the end of this lesson:
cobol1IDENTIFICATION DIVISION. 2PROGRAM-ID. IfStatementDemo. 3DATA DIVISION. 4WORKING-STORAGE SECTION. 501 Account-Balance PIC 9(6). 601 Minimum-Balance PIC 9(6) VALUE 1000. 7PROCEDURE DIVISION. 8 MOVE 1500 TO Account-Balance. 9 IF Account-Balance < Minimum-Balance THEN 10 DISPLAY "Balance is below minimum required." 11 ELSE 12 DISPLAY "Balance is sufficient." 13 END-IF. 14 STOP RUN.
This code demonstrates a simple IF
statement that checks whether an account balance is below a minimum required balance and displays a message accordingly. We'll see "Balance is sufficient." printed in the output.
Let's examine the structure of an IF
statement in COBOL:
IF
statement is followed by a condition that evaluates to either TRUE
or FALSE
.TRUE
, the statements within the IF
block are executed.FALSE
, the statements within the ELSE
block (if present) are executed.In our example above, the IF
statement checks if the Account-Balance
is less than the Minimum-Balance
. If it is, the program displays a message indicating that the balance is below the minimum required. Otherwise, it displays a message indicating that the balance is sufficient.
Note that we can achieve the same result using the LESS
keyword by replacing the IF
condition with the following code:
cobol1IF Account-Balance LESS THAN Minimum-Balance
Similarly, we can use the greater than (>
) operator to check if the balance is above the minimum required balance.
In addition to simple IF
statements, you can also connect multiple conditions using logical operators. One such operator is OR
. When you use OR
, the IF
statement evaluates to TRUE
if any one of the conditions separated by OR
is true.
Let's take a look at an example:
cobol1IDENTIFICATION DIVISION. 2PROGRAM-ID. OrConditionDemo. 3DATA DIVISION. 4WORKING-STORAGE SECTION. 501 Account-Balance PIC 9(6). 601 Minimum-Balance PIC 9(6) VALUE 1000. 701 Warning-Balance PIC 9(6) VALUE 1500. 8PROCEDURE DIVISION. 9 MOVE 1200 TO Account-Balance. 10 IF Account-Balance < Minimum-Balance OR Account-Balance < Warning-Balance THEN 11 DISPLAY "Account needs attention." 12 ELSE 13 DISPLAY "Account is in good standing." 14 END-IF. 15 STOP RUN.
In this example, the IF
statement checks two conditions: whether the Account-Balance
is less than the Minimum-Balance
or less than the Warning-Balance
. If either of these conditions is true, the program displays a message indicating that the account needs attention. If neither condition is true, the program displays a message indicating that the account is in good standing.
In this case as well, we can achieve the same result using the LESS
keyword:
cobol1IF Account-Balance LESS THAN Minimum-Balance OR Account-Balance LESS THAN Warning-Balance
It’s important to understand how logical operators like OR
can enhance the decision-making capabilities of your IF
statements. Using OR
can assist in creating more sophisticated and flexible conditions in your code. Similarly, we can use AND
if we want two conditions to be true at the same time. Always ensure that your conditions are easy to understand and maintain.
Understanding IF
statements is vital for several reasons:
Flow Control: IF
statements allow you to control the flow of your program. They enable you to execute certain sections of code based on whether a condition is true or false.
Error Handling: They are useful for validating data and handling errors, ensuring your program can handle different scenarios gracefully.
Efficiency: Making efficient decisions in your code can also optimize the performance of your application, making it run faster and use resources more effectively.
Excited to dive into the practice section? Let’s get started and equip you with these essential skills for COBOL programming!