i would like to know how to check if a textbox contains numbers i tried the following

If IsNumeric(CategoryTextBox.Text) = True Then

MessageBox.Show("Please delete the digit", "Name warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

End If

Dim chars() As Char = CategoryTextBox.Text

For Each c As Char In chars

If IsNumeric(c) Then

MessageBox.Show("Please delete the digit", "Name warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

Exit For

End If

Next

Dim chars() As Char = CategoryTextBox.Text

For Each c As Char In chars

If IsNumeric(c) Then

MessageBox.Show("Please delete the digit", "Name warning", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)

Exit For

End If

Next

You could do something like this:

thanks bdbodger that works great

As you can see, there are many solutions to this question. Just in case you wanted another one:

This prevents anything that isn't a digit or a control character (such as Tab, Backspace, etc.) from being entered in TextBox1. Stuff still might be pasted in there, though. If you're worried about that, test the whole string for Not(IsNumeric(CType(sender, Textbox).Text)) instead.

IsNumeric is filled with bugs. Regular expressions would be the best choice:

No Adam, IsNumeric is not full of bugs.

Man, this guy has major psychological disorders. He truly is a stalker...

Forum members beware.....Adam is back

Do NOT use IsNumeric to test for presence of all digits. Very few people realize that IsNumeric has multiple features, including the ability to test for hexadecimal values. For example, if the text box includes: &H43

it will be True for IsNumeric. It will also return True for a type Double value, so if you need to test for an integer number, it won't alwayswork.

Better to test each character one by one using the Char.IsDigit method, as pointed out by one of the posters above. You could also use theChar.IsLetter method to solve the problem.

For the opposite problem (which I am mentioning here as general information), you could use the TryParse method to test for an integer, which must include all digits (but can also include a leading minus symbol, which you will have to test for):

Dim num As Integer

If Integer.TryParse(TextBox1.Text, num) Then

MessageBox.Show("OK")

EndIf

My own version of IsNumeric didn't find that to be true:

public static bool IsNumeric(object Expression)

bool isNum;

double retNum;

isNum = Double.TryParse(Convert.ToString(Expression), System.Globalization.NumberStyles.Any, System.Globalization.NumberFormatInfo.InvariantInfo, out retNum);

return isNum;

Solitaire,

The user is not checking the textbox's whole text as a string, but each character. And using my above method would still remove just the digits:

Private Sub RemoveDigits()
Dim temp As String = String.Empty
For i As Integer = 0 To textBox1.Text.Length - 1
If Not IsNumeric(textBox1.Text.Substring(i, 1)) Then
temp += textBox1.Text.Substring(i, 1)
End If
Next
textBox1.Text = temp
End Sub

I know that. I merely included it as general information. I did say that Char.IsDigit or Char.IsLetter should be used to check each character.

Yes it is good info, as I did not know it regarded hexadecimals as values. But I am not a VB developer, i am a C# developer, so I had to create my own IsNumeric..

Thanks Solitaire