Constantes e Enumerações (Visual Basic)

Artigo
08/08/2011

Visual Basic supplies a number of predefined constants and enumerations for developers. Constants store values that remain constant throughout the execution of an application. Enumerations provide a convenient way to work with sets of related constants, and to associate constant values with names.

Constants

Conditional Compilation Constants

The following table lists the predefined constants available for conditional compilation.

Constant	Description
CONFIG	A string that corresponds to the current setting of the Active Solution Configuration box in the Configuration Manager.
DEBUG	A Boolean value that can be set in the Project Properties dialog box. By default, the Debug configuration for a project defines DEBUG. When DEBUG is defined, Debug class methods generate output to the Output window. When it is not defined, Debug class methods are not compiled and no Debug output is generated.
TARGET	A string representing the output type for the project or the setting of the command-line /target option. Os valores possíveis de TARGET são: "winexe" para um aplicativodo Windows. "exe" para um aplicativodo console. "biblioteca" para uma classe biblioteca. "módulo" para um módulo. O /target opção pode ser definida na Visual Studio ambientede desenvolvimento integrado. For more information, see /target (Visual Basic).
TRACE	A Boolean value that can be set in the Project Properties dialog box. By default, all configurations for a project define TRACE. When TRACE is defined, Trace class methods generate output to the Output window. When it is not defined, Trace class methods are not compiled and no Trace output is generated.
VBC_VER	Um número que representa o Visual Basic versão, na principais.secundária formato. O número de versão Visual Basic 2005 é a 8.0.

Print and Display Constants

When you call print and display functions, you can use the following constants in your code in place of the actual values.

Constant	Description
vbCrLf	Combinação de caracteres de retorno/alimentação de linha de carro.
vbCr	Caractere de retorno de carro.
vbLf	Linefeed character.
vbNewLine	Newline character.
vbNullChar	Caractere nulo.
vbNullString	Not the same as a zero-length string (""); used for calling external procedures.
vbObjectError	Error number. User-defined error numbers should be greater than this value. For example: Err.Raise(Number) = vbObjectError + 1000
vbTab	Tab character.
vbBack	Backspace character.
vbFormFeed	Não é usado no Microsoft Windows.
vbVerticalTab	Not useful in Microsoft Windows.

Enumerations

The following table lists and describes the enumerations provided by Visual Basic.

Enumeration	Description
AppWinStyle	Indicates the window style to use for the invoked program when calling the Shell function.
AudioPlayMode	Indicates how to play sounds when calling audio methods.
BuiltInRole	Indica o tipo de função para verificar quando chamar o IsInRole método.
CallType	Indicates the type of procedure being invoked when calling the CallByName function.
CompareMethod	Indicates how to compare strings when calling comparison functions.
DateFormat	Indicates how to display dates when calling the FormatDateTime function.
DateInterval	Indicates how to determine and format date intervals when calling date-related functions.
DeleteDirectoryOption	Specifies what should be done when a directory that is to be deleted contains files or directories.
DueDate	Indicates when payments are due when calling financial methods.
FieldType	Indicates whether text fields are delimited or fixed-width.
FileAttribute	Indicates the file attributes to use when calling file-access functions.
FirstDayOfWeek	Indicates the first day of the week to use when calling date-related functions.
FirstWeekOfYear	Indicates the first week of the year to use when calling date-related functions.
MsgBoxResult	Indicates which button was pressed on a message box, returned by the MsgBox function.
MsgBoxStyle	Indicates which buttons to display when calling the MsgBox function.
OpenAccess	Indicates how to open a file when calling file-access functions.
OpenMode	Indicates how to open a file when calling file-access functions.
OpenShare	Indicates how to open a file when calling file-access functions.
RecycleOption	Specifies whether a file should be deleted permanently or placed in the Recycle Bin.
SearchOption	Specifies whether to search all or only top-level directories.
TriState	Indicates a Boolean value or whether the default should be used when calling number-formatting functions.
UICancelOption	Specifies what should be done if the user clicks Cancel during an operation.
UIOption	Specifies whether or not to show a progress dialog when copying, deleting, or moving files or directories.
VariantType	Indicates the type of a variant object, returned by the VarType function.
VbStrConv	Indicates which type of conversion to perform when calling the StrConv function.