Question

有一些方法可以保护用户只允许字母，数字，和单个空格。说字母我认为只有字母（a-z和A-Z），但没有例如，，Ę，±Ą，śŚ，żŻ等...你能帮我修理下面的代码来检查那个吗？ （不使用正则表达式）

   For Each c As Char In txtSymbol.Text
                If Not Char.IsLetterOrDigit(c) AndAlso c <> "-"c AndAlso c <> " " Then
                    MessageBox.Show("Only lower/upper letters, digits, - and single spaces are allowed"", "Warning", MessageBoxButtons.OK, MessageBoxIcon.Warning)
                    Exit Try
                End If
            Next

有待进一步讨论：

        '--We elping user with leading and ending spaces to be removed and more than one space in same placed to be convert to only one space
        Dim str As String = txtNazwa.Text.Trim         'deleting leading and ending spaces
        While str.Contains("  ")                        'deleting more than one space in same place
            str = str.Replace("  ", " ")
        End While
        txtNazwa.Text = str                            'corrected one we passed to textbox

        'Now we checking further for only those can be presented to pass test:
        '--> single space
        '--> letters a-z  A-Z
        '--> digits
        '--> -
        Dim pattern As String = "^([a-zA-Z0-9-]+\s)*[a-zA-Z0-9-]+$"
        Dim r As New Regex(pattern)

        If Not r.IsMatch(str) Then
            Exit Try
        End If

Answer 1

您可以尝试使用此正则表达式：

^([a-zA-Z0-9-]+\s)*[a-zA-Z0-9-]+$

<强> Regex Demo

在您的代码中，您可以这样尝试：

Dim str As String = "^[a-zA-Z0-9 ]*$"

Dim r As New Regex(str)

Console.WriteLine(r.IsMatch("yourInputString"))

不允许在字符串中使用特殊字符

1 个答案: