Check if numeric

[casox]

How can I check if a value entered into a text box is numeric or not? Thanks.

[MartinLiss]

If IsNumeric(Text1.Text) Then

[zuperman]

IsNumeric Function Example:

This example uses the IsNumeric function to determine if a variable can be evaluated as a number.

Dim MyVar, MyCheck
MyVar = "53"   ' Assign value.
MyCheck = IsNumeric(MyVar)   ' Returns True.
 
MyVar = "459.95"   ' Assign value.
MyCheck = IsNumeric(MyVar)   ' Returns True.
 
MyVar = "45 Help"   ' Assign value.
MyCheck = IsNumeric(MyVar)   ' Returns False.

[HaxSoft]

This stuff should work for integers -- off the top of my head (haven't tried it out though):

Private Function IsNumeric(ByVal argData As String) As Boolean
 
  Dim chrCtr As Long    ' loop counter
  Dim curChr As String  ' current character
 
  If Len(argData) = 0 Then Exit Function
 
  ' Run through the passed-in argument.
 
  For chrCtr = 1 To Len(argData)
    Let curChr = Mid$(chrCtr, argData, 1)                  ' get a character
    If curChr < "0" Or curChr > "9" Then Exit Function ' << BOOMER! not numeric
  Next chrCtr
 
  Let IsNumeric = True  ' set retval (return value)
 
End Function

[MartinLiss]

BTW, I've developed an OCX which is basically a textbox that restricts input to numeric values. It doesn't allow the use of a mask but in addition to the numeric-only restriction and the normal textbox properties it has three new properties which I hope are self-explanatory:
CanBeNegative (Boolean)
CanHaveDecimals (Boolean)
MaxDecimals (Integer)

If anyone is interested I'll attach the OCX.

[Hack]

I'm interested.

(Source code included??)

[MartinLiss]

Sure, why not. Make sure you store the OCX in your Windows System folder. Use the OCX and the code at your own risk. I just wrote it a couple of days ago and haven't spent a lot of time testing it although it seems to work correctly. If you find any bugs or if you have suggestions for improvement, please let me know.

[HaxSoft]

Originally posted by MartinLiss
...I just wrote it ... and haven't spent a lot of time testing it... If you find any bugs ... please let me know.

I found a bug, but it should be simple to work around.

I downloaded the OCX and tried it out. The code seems pretty much OK for English locales ONLY. The decimal point is a comma in most European countries. Anyway, that is not a bug per se ... it is more like a lack of internationalization. The real bug is here:

1) In the number box, type "-153.45"
2) Press <Shift>+<Home>
3) Press <Shift>+<Delete>
4) Press <Shift>+<Insert>
5) Repeat step 4

After these 5 steps, your box will contain "-153.45-153.45".

You need to handle the <Insert> key either by disabling it, but will it then be possible to cause this error using the context menu? I think it would be better to move some of your code from the KeyPress event to the Change event.

Just a suggestion.

[MartinLiss]

Thanks for the feedback. I probably won't do anything about the locale issue because I didn't write the code with distribution in mind, but I will certainly look into the bug you found.