Comments on: looking for isnumeric in vb.net?

By: Billy Bo

Billy Bo — Wed, 02 Dec 2009 16:17:37 +0000

As with all VB coding, you do NOT have to import a Namspace to in order to use it. Just call that namespace.function:

Microsoft.VisualBasic.IsNumeric(expression)

Besides, as Carter says .. if you’re programming in the .NET framework in VB (which if you are programming in VS2003+, then you have no choice), just inherit/import the Microsoft/System namespaces .. You have to the .NET framework installed on the computer anyways to run the program, so you don’t have to worry about NOT having a particular DLL

By: Rex the Strange

Rex the Strange — Tue, 23 Jun 2009 16:12:57 +0000

Why not just use the microsoft.visualbasic namespace version of isnumeric? So much easier that all this that you’ve posted.

By: hong

hong — Wed, 04 Feb 2009 07:25:03 +0000

Use this to the textbox KeyPress event, it accept only number and maximum one “.” and ignore others without add into it:

Private Sub txtMyTextBox_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtSSV.KeyPress

Select Case e.KeyChar
Case Chr(Keys.Back)
e.Handled = False
Case “0″, “1″, “2″, “3″, “4″, “5″, “6″, “7″, “8″, “9″, “.”
Try
Dim strOutput As Double = 0.0
If Double.TryParse(txtSSV.Text & e.KeyChar, strOutput) Then
e.Handled = False
Else
e.Handled = True
End If
Catch ex As Exception
e.Handled = True
End Try
Case Else
e.Handled = True
End Select

End Sub

By: rt07

rt07 — Sat, 31 Jan 2009 23:55:50 +0000

Integer.TryParse(MyText, MyDestNumber)
OR
if Integer.TryParse(MyText, MyDestNumber) then …

if you need decimal values then
Double.TryParse(MyText, MyDestNumber)
OR
if Double.TryParse(MyText, MyDestNumber) then …

By: redmo

redmo — Thu, 30 Oct 2008 23:02:14 +0000

in the keypress event of the textbox, you could add

Dim mychar As Char
mychar = e.KeyChar
If IsNumerical(mychar.ToString) = True Then
‘Insert positive code here
else
msgbox(“Dammit I said numbers only”)

This checks each character as its passed to the txtbox,

By: hacksign23

hacksign23 — Wed, 29 Oct 2008 22:34:58 +0000

oops. here’s the correct one.

public function IsNumeric(ByVal textz as string) as boolean
dim ch as boolean
for each c as byte in System.Text.Encoding.ASCII.getbytes(text)
if (48 <= c <= 57) then
c2 = true â€˜good job.
else
c2 = false â€˜bad job ):
return false
exit function
end if
next
return c2
end function

By: Carter

Carter — Thu, 08 May 2008 14:11:10 +0000

Why reinvent the wheel? IsNumeric is part of .NET. Just use it.

By: Farren

Farren — Sun, 09 Sep 2007 00:44:28 +0000

This seems to work well for me.

Public Shared Function IsNumeric(ByVal sText As String) As Boolean

If Double.TryParse(sText, Globalization.NumberStyles.AllowDecimalPoint) Then
Return True
Else
Return False
End If

End Function

By: JimK

JimK — Thu, 23 Aug 2007 17:01:51 +0000

ok..that didnt paste well…removed some of my code..trying again

Public Shared Function IsNumeric(ByVal sText As String) As Boolean
Dim b As Boolean = True
Dim x As Integer = 0

For x = 0 To sText.Length – 1
Dim sChar As String = sText.Substring(x, 1)

If Asc(sChar) < 48 Or Asc(sChar) > Then
b = False
Exit For
End If
Next

Return b
End Function

By: JimK

JimK — Thu, 23 Aug 2007 17:00:10 +0000

I get nothing but false positives with the functions listed above

I created my own and is perfect for detecting ‘all numeric’ values…great for detecting table indexes (just make sure you trim the text first):

Public Shared Function IsNumeric(ByVal sText As String) As Boolean
Dim b As Boolean = True
Dim x As Integer = 0

For x = 0 To sText.Length – 1
Dim sChar As String = sText.Substring(x, 1)

If Asc(sChar) 57 Then
b = False
Exit For
End If
Next

Return b
End Function