如果在文本框中输入数字，如何将标签更改为红色

Question

简单的问题。我有一个名为lblName的标签和一个名为txtName的文本框。如果在文本框中输入数字，如何使标签字体显示为红色。

Answer 1

Private Sub txtName_TextChanged(sender As Object, e As EventArgs) Handles txtName.TextChanged

    ' Gets the text from the text box.
    Dim text As String = txtName.Text

    ' Checks if the entered text is a number (Only numbers). 
    If IsNumeric(text) Then
        ' Change the label fore color to red.
        lblName.ForeColor = Color.Red
    Else
        ' If the text is not a number, change the color back to black.
        lblNamge.ForeColor = Color.Black
    End If

End Sub