Try Catch Help

Hello all,

I have a datagrid that I have coded to calculate fields by using code like this:

Code:

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Me.DataGridView1.CurrentRow.Cells("Area").Value = _
        ((((Me.DataDataGridView1.CurrentRow.Cells("Diameter").Value) / 2) ^ 2) * 3.14)

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Can someone help me write a try/catch (or something better) that will not have an error if the user leaves the "Diameter" field blank or accidentally types something other than a number?

I'd prefer if the field just stays blank and only calculates if there is a number typed into the field, otherwise show a message box if that's not possible.

Any help greatly appreciated!

vb Code:

dim value as decimal
if decimal.tryparse(Me.DataDataGridView1.CurrentRow.Cells("Diameter").Value,value) then
    Me.DataGridView1.CurrentRow.Cells("Area").Value = _
        (((value / 2) ^ 2) * 3.14)
else
    Me.DataGridView1.CurrentRow.Cells("Area").Value = ""
end if

I get the following error:

Conversion from type 'DBNull' to type 'String' is not valid.

Any thoughts? Thanks.

Me.DataDataGridView1.CurrentRow.Cells("Diameter").Value.tostring

That way still gave me an error, just in a different way. I appreciate your help, it's very hard to try to figure out what people actually want without actually seeing the application first hand. In the dataset developer I set the field type to a string which quit giving me an error and this code I finally got to work by pure dumb luck:

Code:

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If Not IsNumeric(Me.DataDataGridView1.CurrentRow.Cells("Diameter").Value) Then
            MsgBox("Diameter is not valid, please re-enter the diameter.")
        ElseIf Not IsDBNull(Me.DataDataGridView1.CurrentRow.Cells("Diameter").Value) Then
            Me.DataGridView1.CurrentRow.Cells("Area").Value = (((Me.DataGridView1.CurrentRow.Cells("Diameter").Value / 2) ^ 2) * 3.14)

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