Anyone here familiar with Visual Basic? I'm pretty desperate....

I am not VB expert, but I think your error is due to setting an int variable to a text string: invalidcastexception


Dim intNumber As Integer
intNumber = txtNumber.Text

intNumber can take a value 1,2,3,etc

txtNumber.Text

is text so it takes on values like "1","2","3", etc. "1" not equal 1

so what you need to do is parse the string

change this line:

intNumber = txtNumber.Text

to

If Not Integer.TryParse(txtNumber.Text, intNumber ) Then
intNumber = -1
End If

 

It's been awhile since I've coded, but I think this along the lines of what cohete and heypartner mentioned. You should check what the input is first.

if not integer then

don't do anything (or go the extra step and create a message like 'please enter an integer between 1-10)

else

code to convert integer to roman numerals here

It goes with the territory that error handling is a part of programming user interfaces.

 

I concur with Air Langhi said. Since this is VB you can probably find some help MSDN.

 

w3schools.com got me through my programming classes in college.

 

I am not a VB expert, haven't coded in any Windows-based language in a while, but I would agree with most peeps here that you need to declare ALL your variables and their type before using them or even assigning a value to them in memory.

Lastly, have an "if anything else I haven't already covered" option just in case none of the explicitly suggested ones are not chosen.

For example:

if something,
do this
else if something else
do that
else if something else
do something more
for everything else
do this
end

^ Something like that should cover you, even if the conditions above aren't met. It's just covering your butt.

 

Sweatiest owner in NBA history?

 

I was a CIS major for three years and took two courses on VB. I can't tell you exactly how to fix it, but is there something that you can put into the IF statement that commands what to do if there's no input? IDK, but that's the logic that I would use to try to figure it out.

Either that or ditch the integer conversion as suggested. Why are you converting to integers to begin with?

 

Like others have said, it's because you're attempting to convert an empty string into an int. Air Langhi's approach should work. Another approach would be to only execute the TextChanged event code if txtNumber.Text <> "", but I like Air Langhi's better since it checks to see if the number is specifically an integer.