Declares an enumerated type.
Syntax
Enum [typename [ Explicit ] ]
symbolname [= expression] [, ...]
...
End Enum
Parameters
typename
Name of the Enum
symbolname
Name of the constant
expression
A constant expression
Explicit
Requires that symbols must be explicitly referred to by typename.symbolname
Description
Enum, short for enumeration, declares a list of symbol names that correspond to discrete values. If no initial value is given, the first item will be set to
0. Each subsequent symbol has a value one more than the previous unless
expression is given.
Symbols may be each on their own line, or separated on a single line by commas.
An
Enum is a useful way of grouping together a set of related
Constants. A symbol can be accessed like a constant, e.g:
a = symbolname. But if the name clashes with another symbol, it must be resolved using
typename.symbolname. This resolution method is always required if you make the enum
Explicit.
A non-
Explicit Enum declared inside an
Extern ... End Extern block will add its constants to the parent namespace directly, as in C, instead of acting as a namespace on its own. It disallows the
typename.symbolname style of access, and the constants may conflict with other symbols from the parent namespace.
Enum can not contain any member procedure or member data (only symbols), but it can be included (named or unnamed) in a
Type by having.
An
Enum instance can be passed, as any user defined instance, to a procedure (including for the definition of
Overloaded operators).
The size of an
Enum instance will be always that of an
Integer (no matter how many defined symbols are just declarations for the compiler assignment).
Example
Enum MyEnum
option1 = 1
option2
option3
End Enum
Dim MyVar As MyEnum
MyVar = option1
Select Case MyVar
Case option1
Print "Option 1"
Case option2
Print "Option 2"
Case option3
Print "Option 3"
End Select
You can reference formerly declared symbol names within the same enum:
Enum MyEnum
option1 = 1
option2
option3
__
MAX_VALUE = __ -1
End Enum
Print "Option #1:", MyEnum.option1
Print "Option #2:", MyEnum.option2
Print "Option #3:", MyEnum.option3
Print "Max Value:", MyEnum.MAX_VALUE
Output:
Option #1: 1
Option #2: 2
Option #3: 3
Max Value: 3
Dialect Differences
- Explicit Enum not available in the -lang qb dialect unless referenced with the alias __Explicit.
Differences from QB
See also