Question

I have made a vb.net form that has 3 text boxes and a button called Calculate. All I want to do is enter some values to the textboxes and click the button which calculates the numbers. I have done the calculation coding part.

Now I want to enter only numbers to the textboxes and if I enter alphabetics or symbols I need to get an critical error message with ok button when I click the ok button.

How can I do this?

Answer 1

You can use Int32.TryParse (or Double.TryParse) to check if the entered number is an integer (or double, with decimal places).

Dim num As Int32
If Not Int32.TryParse(textBox1.Text, num) Then
    MessageBox.Show("Please enter only integers!", "Critical Warning",
                     MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If

MessageBox.Show Method