Question

下面是我的代码，用于验证我的文本框。目前我只为Letters工作，但我也不知道如何允许间距。

Private Sub txtFirstname_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtFirstname.KeyPress
    If Char.IsLetter(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then
        MessageBox.Show("Letters only.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
        ' Stop invalid character appearing in field
        e.KeyChar = Nothing
    End If
End Sub

Answer 1

使用方法Char.IsWhiteSpace(e.KeyChar)

我还建议使用AndAlso代替And运算符。

If Char.IsLetter(e.KeyChar) = False AndAlso Char.IsControl(e.KeyChar) = False Then

操作员AndAlso避免冗余检查，如果第一个条件为负，则退出。

修改

看起来应该像你有效地实现这个功能一样。您还应将其放在私有子例程中，并在KeyPress处理程序子例程中调用它。以便在要验证输入的每个事件中重用代码

Private Sub txtFirstname_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtFirstname.KeyPress ValidateInput(e) End Sub Private Sub ValidateInput(e As EventArgs) If Char.IsWhiteSpace(e.KeyChar) = False Then If Char.IsLetter(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then MessageBox.Show("Letters only.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error) ' Stop invalid character appearing in field e.KeyChar = Nothing End If End If End Sub

Answer 2

您可以使用以下方式检查：字母，数字和空格（制表符，空格和输入）：

Private Sub textBox1_KeyPress(sender As Object, e As KeyPressEventArgs)
  e.Handled = True
  Dim IsLetter As Boolean = (e.KeyChar >= 65 AndAlso e.KeyChar <= 90) OrElse (e.KeyChar >= 97 AndAlso e.KeyChar <= 122)
  Dim IsNumber As Boolean = (e.KeyChar >= 48 AndAlso e.KeyChar <= 57)
  Dim IsWhiteSpace As Boolean = (e.KeyChar = 9) OrElse (e.KeyChar = 13) OrElse (e.KeyChar = 32)
  If IsLetter OrElse IsWhiteSpace OrElse IsNumber Then
    e.Handled = False
    MessageBox.Show("Just numbers and letters and whitespaces")
  End If
End Sub

KeyPress字母和间距

2 个答案: