在 vb.net 中验证文本框 [英] validate a textbox in vb.net

问题描述

如何验证 vb.net 中的文本框，以便在我输入字母以外的任何内容时显示错误消息

How could i validate a textbox in vb.net, so that it gives error message if i enter anything apart from alphabets

推荐答案

您可以检查文本字符串，即 textbox1.text，以确保它在 .Leave 事件中除了字母字符之外没有任何内容.例如，当用户切换到下一个控件时，这将捕获错误.您可以使用正则表达式执行此操作(在此示例中导入 System.Text.RegularExpressions)，或者您可以手动"检查文本.

You can check the text string, i.e., textbox1.text, to make sure it has nothing besides alphabet characters in the .Leave event. This will catch an error when the user tabs to the next control, for example. You can do this using a regular expression (import System.Text.RegularExpressions for this example), or you can check the text "manually."

Private Sub TextBox1_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox1.Leave
  If Not Regex.Match(TextBox1.Text, "^[a-z]*$", RegexOptions.IgnoreCase).Success Then
    MsgBox("Please enter alpha text only.")
    TextBox1.Focus()
  End If
End Sub

如果您想在用户按下非 alpha 键时立即停止，您可以使用 TextChanged 事件而不是 .Leave 事件.

If you want to stop the user as soon as a non-alpha key is pressed, you can use the TextChanged event instead of the .Leave event.

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