return enum value

Question

I am wanting a function that will return the value of a an enum, the case below.. "Data1" is passed to the function and the function would return 1

Public Enum MyData

        Data1 = 1

        DAta2 = 2

end enum

Answer 1

Hello,

This

Public Function test(sender As MyData) As Integer
    Return sender
End Function

When called

Console.WriteLine(test(MyData.Data1))

Returns 1

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Answer 2

No special functions required. If you declare your enum as an Integer, you the enum value IS the integer. See example:

    Private Sub TestEnums()
        Dim SomeEnum As MyData = MyData.Data1
        MessageBox.Show(SomeEnum)
        MessageBox.Show(SomeEnum.ToString())
    End Sub

    Public Enum MyData As Integer
        Data1 = 1
        Data2 = 2
    End Enum

Answer 3

Ok.. this might help a bit more... I am using the Data1, Data2 in a combobox....  I want the user to select Data1 or Data2 and return the numberic value so I can do an update in a database.  so I thinking I need to pass to the function, the string value of the combobox and somehow get the interger value back.

Answer 4

Ok.. this might help a bit more... I am using the Data1, Data2 in a combobox....  I want the user to select Data1 or Data2 and return the numberic value so I can do an update in a database.  so I thinking I need to pass to the function, the string value of the combobox and somehow get the interger value back.

You're already there - that's what they're trying to say.

Public Enum MyData
    Data1 = 1
    DAta2 = 2
End Enum

Then if I run this:

Dim test As MyData = MyData.DAta2
Dim test2 As Integer = test
Stop

test2 equals the integer value of two (2). Make sense?

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Please call me Frank :)

Answer 5

Ah, then you want Enum.TryParse(). No function required:

    Private Sub TestEnums()
        Dim StringEnum As String = "Data1"
        Dim SomeEnum As MyData
        [Enum].TryParse(StringEnum, SomeEnum)
        MessageBox.Show(SomeEnum & ", " & SomeEnum.ToString())
    End Sub

    Public Enum MyData As Integer
        Data1 = 1
        Data2 = 2
    End Enum

Enum.TryParse() returns a boolean indicating success. It accepts a value to attempt to parse, as well as where the value should go if the parsing is successful.

Answer 6

If you loaded the ComboBox with the members via GetNames then we have

So if Data1 is selected we need to convert the Text property of the ComboBox to an Enum which can be done by placing the following code into a code module, not a class or form file.

''' <summary>
''' Convert a string to an enum member
''' </summary>
''' <typeparam name="T">Enum</typeparam>
''' <param name="sender">String value that represents a valid enum member for T</param>
''' <returns>Enum member or throws an exception if sender is not valid for T</returns>
<System.Diagnostics.DebuggerStepThrough()> _
<System.Runtime.CompilerServices.Extension()> _
Public Function ToEnum(Of T)(ByVal sender As String) As T

    Dim TheType As Type = GetType(T)

    If [Enum].IsDefined(GetType(T), sender) Then
        Return CType(System.Enum.Parse(TheType, sender, True), T)
    Else

        Dim BaseType As String = TheType.ToString
        Dim Pos As Integer = BaseType.IndexOf("+")
        Dim ErrorMessage As String = ""

        If Pos > -1 Then
            Dim EnumName As String = BaseType.Substring(Pos + 1)
            ErrorMessage = String.Format("'{0}' not a member of '{1}'", sender, EnumName)
        Else
            ErrorMessage = String.Format("{0} not a member of {1}", sender, TheType)
        End If

        Throw New Exception(ErrorMessage)

    End If
End Function

Place a button on the form and use this

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Demo(ComboBox1.Text.ToEnum(Of MyData)())
End Sub
Public Sub Demo(ByVal SomeValue As Integer)
    Console.WriteLine(SomeValue)
End Sub

Now what I like to do is use an extension method to populate the ComboBox

ComboBox1.DataSource = GetType(MyData).Names.ToList

Extension method for the above

''' <summary>
''' Return list of names for a specific enum
''' </summary>
''' <param name="sender">String</param>
''' <returns>String array of enum names</returns>
<System.Runtime.CompilerServices.Extension> _
Public Function Names(ByVal sender As Type) As String()
    Return System.Enum.GetNames(sender)
End Function

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Please remember to mark the replies as answers if they help and unmark them if they provide no help, this will help others who are looking for solutions to the same or similar problem.

Answer 7

Thanks Chip....

I was not thinking.. I was doing

console.writeline([enum].tryparse(stringenum, someenum)

Thanks again for all the help

Answer 8

thanks for the ideas ;)