In this section, we will delve into the concept of variables in Control Language (CL). Understanding variables is crucial as they are fundamental to storing and manipulating data within your CL programs.

A variable in CL is a storage location identified by a name that holds data which can be modified during the execution of a program. Variables allow you to store data temporarily and use it throughout your program.

• Variable Name: A unique identifier for the variable.
• Data Type: The type of data the variable can hold (e.g., numeric, character).
• Value: The actual data stored in the variable.

In CL, variables can be broadly categorized into two types:

1. Local Variables: Defined within a procedure or a block and can only be accessed within that scope.
2. Global Variables: Defined outside of any procedure or block and can be accessed from anywhere in the program.

• Character (CHAR): Used to store text.
• Decimal (DEC): Used to store numeric values with decimal points.
• Integer (INT): Used to store whole numbers.

To declare a variable in CL, you use the DCL (Declare) command. The syntax for declaring a variable is as follows:

In this example:

• &Name is a character variable with a length of 20.
• &Age is a decimal variable with a length of 3 digits and 0 decimal places.
• &Counter is an integer variable with a length of 5 digits.

You can assign values to variables using the CHGVAR (Change Variable) command. The syntax is:

In this example:

• &Name is assigned the value 'John Doe'.
• &Age is assigned the value 30.
• &Counter is assigned the value 1.

Variables can be used in expressions to perform calculations or manipulate data. Here’s an example of using variables in an arithmetic expression:

In this example:

• &Num1 and &Num2 are decimal variables.
• &Sum is calculated by adding &Num1 and &Num2.

1. Declare a character variable &City with a length of 15.
2. Declare a decimal variable &Temperature with a length of 4 digits and 1 decimal place.
3. Assign the value 'New York' to &City.
4. Assign the value 23.5 to &Temperature.

1. Declare two integer variables &NumA and &NumB with a length of 3.
2. Declare an integer variable &Result with a length of 3.
3. Assign the value 7 to &NumA and 5 to &NumB.
4. Calculate the sum of &NumA and &NumB and store it in &Result.

• Incorrect Data Type: Ensure the data type matches the kind of data you intend to store.
• Length Mismatch: Be mindful of the length specified for the variable, especially for character and decimal types.
• Uninitialized Variables: Always initialize variables before using them in expressions to avoid unexpected results.

In this section, we covered the basics of variables in CL, including their types, declaration, assignment, and usage in expressions. Understanding these concepts is essential for writing effective CL programs. In the next section, we will explore how to define and use variables in more detail.