eva/3 Application Builder • Developing eva/3 Applications

Working with expressions

Expressions allow the calculation of values under comprehension of values from form- or report components.

An expression can be composed from one or more of the following parts:

Expressions
Operators	Operators connect the operands with a function. Assisted are the basic arithmetic operations and logical- and relational operators.
Fuctions	Functions achieve operations with no or more values or rather arguments.
Objects	Objects allow the access at for Example components or forms and their values, properties and functions.
Constants	Constants are specified terms like true, false or null
Strings	Strings are free text definitions,which can be connected with other operands.
Numbers	Numbers are values which for Example combined with the Operatoren can be used for the basic arithmetics.
Date	The date describes the values, which define a moment.
Array	An Array combines different values, also from several datatypes.
Variables	Variables can contain any kind of value or object.
Control structures	Control structures allows to modify the execution chain.

Syntax

An expression is branded trough a leading "="-character and is made up of a function, a object, a constant, number or string. Consists an expression of more than one of the mentioned parts, so are those to connect by operators. The upper- and lowercase is marginal with the exception of objects and object functions.

An expression can (but not must) be finished with a trailing ';' character. After finishing another expession statement can follows but this one will not be used for the expression result. For creating value assignments to the first expression part, variables can be used.

Developing eva/3 Applications
Constants
Control structures
Date
Numeric values
Objects
Operators
Strings
Syntax
Value lists (Arrays)
Variables
Expression-Editor
functions