VBScript in a Nutshell, 2nd Edition

Name

Const Statement

Syntax

[Public|Private] Const constantname = constantvalue

constantname

Use: Required

The name of the constant.

constantvalue

Use: Required

Data Type: Numeric or String

A constant value, and optionally, the + and - unary operators. Unlike variables, constants must be initialized.

Description

Declares a constant value; i.e., its value can’t be changed throughout the life of the program or routine. One of the ideas of declaring constants is to make code easier to both write and read; it allows you to replace a value with a recognizable word.

Rules at a Glance

• The rules for constantname are the same as those of any variable: the name can be up to 255 characters in length and can contain any alphanumeric character or an underscore, although it must start with an alphabetic character. As is the case with variable names, these rules can be overridden by placing brackets around the constant name.

• constantvalue can be a string or numeric literal. It can be only a single value (a simple constant); that is, it cannot be an expression that includes a call to an intrinsic or user-defined function, property, or method, nor can it contain any arithmetic or string operators or variables. In addition, a constant can’t be defined in terms of another constant, as in the statement:

  Public Const CDATE = CSTART_DATE    ' Invalid

Example

Private Const  my_Constant = 3.1417

Programming Tips and Gotchas

• The recommended coding convention for constants is the same as variables: use camel casing. This places ...