Question

所以，我做了一些研究，但没有提出任何答案。我读到了关于正则表达式的方法，但我在这方面几乎是新的，我从未听说过它。

我尝试做的是确定用户是否输入了密码（在我的情况下我称之为＃34;学号和＃34;），该密码必须只包含一个大写字母S，八个数字在大写字母S之后，最后是一个特殊字符*（特别是按此顺序）。

我已经编程了这个：

Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click

        Dim InvalidName As Integer = 0
        Dim InvalidStudentNumber_Numeric As Integer = 0

        For intIndex = 0 To txtName.Text.Length - 1
            If IsNumeric(txtName.Text.Substring(intIndex, 1)) Then
                InvalidName = 1
            End If
        Next

        For intIndex = 0 To txtStudentNumber.Text.Length - 1
            If IsNumeric(txtStudentNumber.Text.Substring(intIndex, 1)) Then
                InvalidStudentNumber_Numeric += 1

            End If
        Next

        If InvalidName <> 0 Then
            MessageBox.Show("The name entered does not meet the characters criteria.  Provide a non-numeric name, 10 characters or longer.",
                            "Invalid Information: Name")
            txtName.Focus()

        ElseIf InvalidStudentNumber_Numeric <> 8 Then
            MessageBox.Show("The student number entered does not meet the characters criteria.  Provide a non-numeric student number, 10 characters long.",
                            "Invalid Information: Student Number")
            txtStudentNumber.Focus()

所以，对于学生的姓名，我没有任何问题，但密码就是让我的。我已经知道如何知道它是否有数字（它必须有8），但我不知道如何在字符串的开头搜索大写的S和字符串末尾的*。

Answer 1

不需要正则表达式。

Public Function IsValidStudentNumber(ByVal id As String) As Boolean
    '  Note that the `S` and the `*` appear to be common to all student numbers, according to your definition, so you could choose to not have the users enter them if you wanted.
    Dim number As Int32 = 0

    id = id.ToUpper

    If id.StartsWith("S") Then
        ' Strip the S, we don't need it.
        ' Or reverse the comparison (not starts with S), if you want to throw an error.
        id = id.Substring(1)
    End If

    If id.EndsWith("*") Then
        ' Strip the *, we don't need it.
        ' Or reverse the comparison (not ends with *), if you want to throw an error.
        id = id.Substring(0, id.Length - 1)
    End If

    If 8 = id.Length Then
        ' Its the right length, now see if its a number.
        If Int32.TryParse(id, number) Then
            Return True
        End If
    End If
    Return False
End Function

如何在VB.net？

1 个答案: