calculator needs to "see" wrong input

[ph03nix]

Hello,

I'm making a calculator with four buttons (*, /, - and +). pressing one of the four buttons should calculate the desired function from two Textboxes and put it in a third one. The problem is that it has to give an error if one of the two inputs is not a number.... i just don't know how to program this.. please help, i'm just a beginner

thanx in advance

 

[CajunCenturion]

You might try the following:

Sub cmdButton_Click

if (isnumeric(editbox1.text)) then
if (isnumeric(editbox2.text)) then
PerformCalculation
else
msgbox "Operand 2 is not Numeric"
end if
else
msgbox "Operand 1 is not Numeric"
endif

End Sub


IsNumeric is a built-in function of VB.

Good Luck

 

[ph03nix]

Thanx

 

[dsi]

Just be forewarned that some text is recognized as numeric. This should not affect your calculations though.
For example:
IsNumeric("3d4&quot returns True

 

[CajunCenturion]

dsi is correct. A simple workaround for that is the following code:

if trim(str(val(editbox.text))) = trim(editbox.text) then
it only contains numeric characters
else
its invalid
end if

Good Luck

 

[kford02]

This may be simplistic but you can also limit the input to your boxes with this. It would not allow them to enter anything but numbers.

Private Sub Text2_KeyPress(KeyAscii As Integer)
If KeyAscii < 48 Or KeyAscii > 57 Then
KeyAscii = 0
Beep
(enter the numbers into your variables here)
End If

You can insert appropriate messages if you want but with the beeps they eventually get the idea. And you would have to do this for every textbox.