Expressions - Introduction

An expression is made up of operators, variables and functions, and these are evaluated according to a specific precedence to produce a result.

Data Types

Each variable, operand, function parameter and result has a value which can be one of the supported data types.

Operators

An operator specifies an operation, or calculation, that is performed on one or two elements in an expression.

Unary operators operate on a single value
Combination operators generate a single value based on two source values
Comparison operators generate a Boolean value based on the relative values of two source values
Logical operators generate a Boolean value based on two source Boolean values

Functions

In order to manipulate the values provided by variables, ServerAssist provides a range of functions. These functions operate on one or more variables.

String functions provide string processing capabilities
Date functions provide date processing capabilities
Conversion functions change from one data type to another
Analysis functions allow variable contents to be examined
Decision functions allow alternative return values based on a Boolean value

Precedence

The different parts of an expression are evaluated in a specific order. In particular each operator has a certain priority, so that they are always evaluated in a consistent sequence.

Operators have a defined precedence order
Parentheses can be used to alter the evaluation order