How to: Declare Enumerations

You create an enumeration with the Enum statement in the declarations section of a class or module. You cannot declare an enumeration within a method. To specify the appropriate level of access, use Private, Protected, Friend, or Public.

An Enum type has a name, an underlying type, and a set of fields, each representing a constant. The name must be a valid Visual Basic 2005 qualifier. The underlying type must be one of the integer types—Byte, Short, Long or Integer. Integer is the default. Enumerations are always strongly typed and are not interchangeable with integer number types.

Enumerations cannot have floating-point values. If an enumeration is assigned a floating-point value with Option Strict On, a compiler error results. If Option Strict is Off, the value is automatically converted to the Enum type.

For information on names, and how to use the Imports statement to make name qualification unnecessary, see Enumerations and Name Qualification.

To declare an enumeration

1. Write a declaration that includes a code access level, the Enum keyword, and a valid name, as in the following examples, each of which declares a different Enum.

   Private Enum SampleEnum
           SampleMember
       End Enum 
       Public Enum SampleEnum2
           SampleMember
       End Enum 
       Protected Enum SampleEnum3
           SampleMember
       End Enum 
       Friend Enum SampleEnum4
           SampleMember
       End Enum 
       Protected Friend Enum SampleEnum5
           SampleMember
       End Enum
   

2. Define the constants in the enumeration. By default, the first constant in an enumeration is initialized to 0, and subsequent constants are initialized to a value of one more than the previous constant. For example, the following enumeration, Days, contains a constant named Sunday with the value 0, a constant named Monday with the value 1, a constant named Tuesday with the value of 2, and so on.

   Public Enum Days
     Sunday
     Monday
     Tuesday
     Wednesday
     Thursday
     Friday
     Saturday
   End Enum
   

3. You can explicitly assign values to constants in an enumeration by using an assignment statement. You can assign any integer value, including negative numbers. For example, you may want constants with values less than zero to represent error conditions. In the following enumeration, the constant Invalid is explicitly assigned the value –1, and the constant Sunday is assigned the value 0. Because it is the first constant in the enumeration, Saturday is also initialized to the value 0. The value of Monday is 1 (one more than the value of Sunday); the value of Tuesday is 2, and so on.

   Public Enum WorkDays
     Saturday
     Sunday = 0
     Monday
     Tuesday
     Wednesday
     Thursday
     Friday
     Invalid = -1
   End Enum
   

This code example is also available as an IntelliSense code snippet. In the code snippet picker, it is located in Visual Basic Language. For more information, see How to: Insert Snippets Into Your Code (Visual Basic).

To declare an enumeration explicitly

• Write a declaration using the following syntax.

  Public Enum MyEnum As Byte
    Zero
    One
    Two
  End Enum
  

See Also

Tasks

How to: Refer to an Enumeration Member

How to: Iterate Through An Enumeration in Visual Basic

How to: Determine the String Associated with an Enumeration Value

Concepts

Enumerations and Name Qualification

When to Use an Enumeration

Intrinsic Constants and Enumerations

Constant and Literal Data Types

Other Resources

Constants in Visual Basic