Progress
Language Tutorial
for Windows
Summary
An expression is a combination of 4GL language elements that results in a value. At a minimum, an expression consists of one operand, but can include multiple operands, operators, and functions.
An operand is a language element that represents a value. Operands include:
- Variables — A location in memory that holds a value that may change during the execution of a procedure.
- Database fields — An individual value from a database record.
- Widget attributes — A value that describes a characteristic of a widget like its width, height, and so on.
- Constants — A value that does not change during the execution of a procedure.
An operator is a language element that represents an action carried out on one or more operands.
An operation, is the successful combination of operands and operators that results in a value.
A function is a prewritten program that performs a specific task and returns a value. There are two types of functions in Progress: pre-defined functions that Progress provides and user-defined functions that you can create.
Arrays are fields or variables that contain multiple data elements. The extent of an array is the number of elements it contains.
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