Variables in CLLE

Learning Objective

By the end of this lesson, you will be able to declare a CL variable using DCL, recognize common CL data types, and change a variable's value using CHGVAR.

Simple Explanation

In the CLLE Program Structure lesson, you saw a DCL statement without a detailed explanation of its parts. This lesson looks specifically at CL variables: how they are declared, what data types are common, and how their values are changed.

A CL variable is declared using DCL, specifying the variable's name, type, and, for some types, a length:

DCL VAR(&CUSTNAME) TYPE(*CHAR) LEN(30)
DCL VAR(&ORDERTOTAL) TYPE(*DEC) LEN(9 2)
DCL VAR(&ORDERCOUNT) TYPE(*INT) LEN(4)

Common CL data types include:

• *CHAR: character (text) data, similar to char in RPGLE.
• *DEC: decimal numeric data, with a length specifying total digits and decimal digits, similar to packed in RPGLE.
• *INT: whole number (integer) data.
• *LGL: logical data, holding a simple true/false style value.

Every CL variable name starts with an ampersand (&). Once declared, a variable's value is changed using CHGVAR (Change Variable), giving the variable's name and its new value:

CHGVAR VAR(&CUSTNAME) VALUE('Jordan Lee')
CHGVAR VAR(&ORDERTOTAL) VALUE(100.00)

Why It Matters

CL variables let a CLLE program hold and work with changing values, such as a customer name being processed, an order total, or a count of records handled so far, in the same way variables serve this purpose in RPGLE. Recognizing DCL and CHGVAR, and common CL data types like *CHAR and *DEC, is foundational to reading or writing any CLLE program that does more than run a fixed sequence of commands.

Practical Example

Imagine a CLLE program that keeps track of how many records it has processed so far, using a variable declared as DCL VAR(&ORDERCOUNT) TYPE(*INT) LEN(4). As the program runs, it uses CHGVAR to update &ORDERCOUNT each time it processes another record, letting later parts of the program, such as a message reporting how many records were handled, refer to that same, current count.

This is a simplified, illustrative example rather than a specific real program, but it reflects a very common, everyday use of CL variables in CLLE programs.

Common Confusions

*"Is DEC in CL the same thing as packed in RPGLE?" They serve the same general purpose, holding decimal numeric data with a specified number of total and decimal digits, though *DEC is CL's own keyword for this, distinct from RPGLE's packed data type.

"Do I need to use CHGVAR every time I want to give a variable an initial value?" Not always. DCL itself can optionally include an initial value using the VALUE keyword parameter. CHGVAR is used specifically to change a variable's value after it has already been declared, whether that is the first meaningful assignment or a later update.

"Can a CL variable change its data type after it is declared?" No. Like RPGLE variables, a CL variable's data type is fixed once declared by DCL and cannot change while the program runs.

Quick Recap

• DCL declares a CL variable, specifying its name, type, and, for some types, a length; every CL variable name starts with &.
• Common CL data types include *CHAR (text), *DEC (decimal numbers), *INT (whole numbers), and *LGL (true/false values).
• CHGVAR changes a variable's value after it has been declared.
• CL variables let a CLLE program hold and work with changing values, the same general purpose variables serve in RPGLE.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "Can I give a CL variable an initial value directly in its DCL statement?"
• "What is the CL equivalent of RPGLE's ind data type?"