Decidindo o tipo de variável a ser definido (Visual Basic)
When you define a variable, you must decide the following characteristics:
Its data type — what kind of data it should hold
Its lifetime — how long it should continue to exist
Its scope — what code should be able to refer to it without qualifying its name
Its access level — what code should have permission to read and write to it
Data Type
In the Instrução Dim (Visual Basic) that declares the variable, include an As clause specifying the appropriate data type (such as Integer or String). The following pages can help you choose a variable's data type.
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For more information, see Resumo de tipo de dados (Visual Basic).
Lifetime
The important decision in lifetime is whether it is acceptable for the variable to cease to exist when the module, class, or procedure that declares it ceases to exist.
If the variable does not need to continue existing beyond the lifetime of its containing element, you do not need to do anything else. If the variable needs to continue to exist longer than its containing element, you can include the Static or Shared keyword in its Dim statement. For more information, see Tempo de vida no Visual Basic.
Scope
A variable's scope is normally the same as its declaration space, that is, the containing element in which it is declared. You must decide how extensive the variable's scope should be.
Be sure the Dim statement appears at the appropriate level, such as block, procedure, or module level. Follow the steps described in Como: Controlar o escopo de uma variável (Visual Basic).
For more information, see O Escopo no Visual Basic.
Access Level
Every variable has a default access level that depends where it is declared, that is, in what type of containing element.
If you need to specify an access level other than the default, you can include an access modifier (such as Protected or Private) in its Dim statement. You can do this only for member variables (namely, variables declared outside a procedure). Follow the steps described in Como: Controlar a disponibilidade de uma variável (Visual Basic).
For more information, see Níveis de acesso em Visual Basic.
Consulte também
Tarefas
Como: Controlar o escopo de uma variável (Visual Basic)
Referência
Conceitos
Declaração de variável no Visual Basic