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Text Box Validation In Vb.net

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2 replies to this topic

#1 RandomSkratch


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Posted 03 February 2006 - 05:57 PM

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)


Perform the proper calculations (these are also already done)


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.


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#2 Jay Cat

Jay Cat

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Posted 04 February 2006 - 05:26 PM

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

#3 tsg1zzn


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Posted 13 February 2006 - 06:23 AM

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:
FUNCTION IsNumeric(s$) AS INTEGER 'Do you have a boolean type in VB.NET?
  Result.l = 1
  For i.l = 0 To Len(s$)
	If Mid(s$, I, 1) < "0" Or Mid(s$, I, 1) > "9"
	  Result = 0
  RETURN Result

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