Question

I’m doing a basic homework assignment which looks like this:

    While input <> -1         input = CDbl(InputBox('Enter numbers to add, enter -1 to stop'))         values = values + input     End While 

It works fine until I press ‘cancel’ on the input box. Then the string input is ”, and I get the following error:

System.InvalidCastException {'Conversion from string ''                                to type 'Double' is not valid.'} 

I think I understand the error, I’m trying to convert using CDbl a non-numeric value. My question is what would be a more proper way to write this code? Is it the code, or just a lack of error handling?

Answer 1

Try using Double.TryParse

Dim value as Double = Nothing If Double.TryParse(InputBox('Enter numbers...'), value) Then     values = values + value End If 

My syntax may be a bit off, but you should get the idea