hello i am stuck writing a code in visual basics. i keep getting an error messag

Question

hello i am stuck writing a code in visual basics. i keep getting an error message and i dont know how to fix it. the error message reads " structure 'double' cannot be indexed because it has no default propert" im not sure what that means.

Option Strict On
Public Class InchesToMetric
    Private Sub MillimetersButton_Click(sender As Object, e As EventArgs) Handles MillimetersButton.Click

        Dim Inches As Double         ' To hold the inches
        Dim Millimeters As Double    ' To hold the millimeters

        Try
            ' Get the inches.
            Inches = CDbl(InchesText.Text)

            ' Convert inches to millimeters.
            Millimeters = INCHESTOMM(Inches)

            ' Display the result.
            MessageBox.Show(Inches.ToString() & " inches equals " &
                            Millimeters.ToString() & " millimeters.")
        Catch
            ' Display an error message for invalid input.
            MessageBox.Show("Error: Enter a numeric value.")
        End Try

    End Sub

this is the module that i want it to get the information from

Option Strict On
Module MathModule

    ' Constants for the meters to English conversion factors
    Public Const METERSTOINCHES As Double = 39.37
    Public Const METERSTOFEET As Double = 3.28
    Public Const METERSTOYARDS As Double = 1.09

    ' Constants for the inches to metric conversion factors
    Public Const INCHESTOMM As Double = 25.4
    Public Const INCHESTOCM As Double = 2.54
    Public Const INCHESTOMETERS As Double = 0.0254

    ' The MetersToInches function accepts a number of meters as
    ' an argument and returns the equivalent number of inches.
    Public Function MetersToInchesReturn(ByVal Meters As Double) As Double
        Return Meters * METERSTOINCHES
    End Function

    ' The MetersToFeet function accepts a number of meters as
    ' an argument and returns the equivalent number of feet.
    Public Function MetersToFeetReturn(ByVal Meters As Double) As Double
        Return Meters * METERSTOFEET
    End Function

    ' The MetersToYards function accepts a number of meters as
    ' an argument and returns the equivalent number of yards.
    Public Function MetersToYardsReturn(ByVal Meters As Double) As Double
        Return Meters * METERSTOYARDS
    End Function

    ' The InchesToMM function accepts a number of inches as
    ' an argument and returns the equivalent number of millimeters.
    Public Function InchesToMMReturn(ByVal Inches As Double) As Double
        Return Inches * INCHESTOMM
    End Function

    ' The InchesToCM function accepts a number of inches as
    ' an argument and returns the equivalent number of centimeters.
    Public Function InchesToCMReturn(ByVal Inches As Double) As Double
        Return Inches * INCHESTOCM
    End Function

    ' The InchesToMeters function accepts a number of inches as
    ' an argument and returns the equivalent number of meters.
    Public Function InchesToMetersReturn(ByVal Inches As Double) As Double
        Return Inches * INCHESTOMETERS
    End Function
End Module

Explanation / Answer

I've gone through the code and the error message both.

The error is coming because of the name here in the following line in your code..

Millimeters = INCHESTOMM(Inches)

See, in your module MathModule, you are defining few constants that are useful for conversions right. One of them is INCHESTOMM which you've defined as type double.

The function which returns the value from inches to mm is named here as InchesToMMReturn() and its return type is also double. This function is using the constant you defined above.

So, in order to get this conversion, you should write

Millimeters = INCHESTOMMReturn(Inches)

This is the function which does the specified task.

In your code, you're passing the argument to the constant, it is not a function. And as it is of type double, you're getting this error.

So, simply change the constant name to function name in that line and the code is good to go. This may have happened due to name similarity. The code is right.

Do comment if there is any query. Thank you. :)

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