I was wondering how I would go about writing this IF statement for validation of data entered into certain text boxes.

IF data entered into QuantityTextBox.Text = Letters Then

Display Error (I can do the error msg)

ELSE

Perform the proper calculations (these are also already done)

END IF


I don't know how to say if the text box is = numerical values or alphabetical values. I've checked my school text book and the VB Help files but so far nothing.

Thanks

I would use the KeyPress event to prevent letters from being entered.

Now I have never touched VB.Net, but here's some suggestions:

Do you have a function for returning only the numbers in a string? If so, you can assume that the string contains only numbers if the (length of string) = (length of onlynumbers(string)).

Since this .Net, I would assume that the text box has an input mask property for this very purpose.

Or, you can write a function yourself which walks through each character in the string and checks if it is numeric: