Const Statement

Description

Declares constants for use in place of literal values.

Syntax

[Public | Private] Const constname [As type] = expression

The Const statement syntax has these parts

Part	Description

Public	Optional. Keyword used at module level to declare constants that are available to all procedures in all modules. Not allowed in procedures.
Private	Optional. Keyword used at module level to declare constants that are available only within the module where the declaration is made. Not allowed in procedures.
constname	Required. Name of the constant; follows standard variable naming conventions.
type	Optional. Data type of the constant; may be Byte, Boolean, Integer, Long, Currency, Single, Double, Decimal (not currently supported), Date, String, or Variant. Use a separate As type clause for each constant being declared.
expression	Required. Literal, other constant, or any combination that includes all arithmetic or logical operators except Is.

Remarks

Constants are private by default. Within procedures, constants are always private; their visibility can't be changed. In standard modules, the default visibility of module-level constants can be changed using the Public keyword. In class modules, however, constants can only be private and their visibility can't be changed using the Public keyword.

To combine several constant declarations on the same line, separate each constant assignment with a comma. When constant declarations are combined in this way, the Public or Private keyword, if used, applies to all of them.

You can't use variables, user-defined functions, or intrinsic Visual Basic functions (such as Chr) in expressions assigned to constants.

Note Constants can make your programs self-documenting and easy to modify. Unlike variables, constants can't be inadvertently changed while your program is running.

If you don't explicitly declare the constant type using As type, the constant has the data type that is most appropriate for expression.

Constants declared in a Sub, Function, or Property procedure are local to that procedure. A constant declared outside a procedure is defined throughout the module in which it is declared. You can use constants anywhere you can use an expression.

See Also

#Const directive, Deftype statements, Function statement, Let statement, Property Get statement, Property Let statement, Property Set statement, Sub statement.

Specifics (Microsoft Access)

A constant in a Microsoft Access standard module is private by default. If you precede a constant with the keyword Public, however, it is then available to other modules in the current database. It is also available to modules that reference the current database.

A constant defined in a class module is always private to that module, and can't be made public by using the Public keyword.

Example

This example uses the Const statement to declare constants for use in place of literal values. Public constants occur in the General section of a standard module, rather than a class module. Private constants can go in the General section of any type of module.

' Constants are Private by default.
Const MyVar = 459

' Declare Public constant. 
Public Const MyString = "HELP"

' Declare Private Integer constant.
Private Const MyInt As Integer = 5

' Declare multiple constants on same line.
Const MyStr = "Hello", MyDouble As Double = 3.4567

Example (Microsoft Access)

In Microsoft Access, you cannot declare public constants in the Declarations section of a class module. Constants in a class module must be private. You can declare both public and private constants in the Declarations section of a standard module.

' In class module.
Const conCommission As Single = .08

' In standard module.
Const conErrorNumber As Integer = 91
Public Const conAddress As String = "8421 58th Avenue, College Park, MD"