What is an Expression?

In This Lesson, You Will Learn:

• The definition of an expression.
• The three types of component that can make up an expression: identifier, operator and literal.
• How to assemble a basic expression.
• Valid naming conventions for identifiers in the KnowledgeKube Expression Engine.

In programming, an expression is a piece of code used to perform a task and return a value. Expressions are built using a combination of Identifiers, Operators and Literals. You can use an expression to calculate values, validate data, and set a default value for a field or control.

The following example expression contains all of these elements:

Sum() and PurchasePrice are both examples of identifiers, the asterisk symbol (*) is an arithmetic operator, and "0.08" is a literal.

An expression can be as complex or as simple as its purpose dictates. The following expression is less complex than the previous example, containing a single operator and a single literal:

The above example returns True when it is compared to a number that is greater than 0, and False when it is compared to a number that is less than or equal to 0.

 

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