Question

我正在使用第7个字符的校验位。程序以有效输入运行。当我故意使用错误的校验位时，我的if语句不会执行？无法弄清楚为什么我在后续的其他功能运行时不会执行。

 Private Sub btnEnter_Click(sender As Object, e As EventArgs) Handles btnEnter.Click
    Dim Sel As Integer, test As Boolean = False
    Dim PointerA As Integer
    txtResult.Clear()
    While test <> True And Sel < StudentNameArray.Length
        If radName.Checked = True Then
            If txtInput.Text = StudentNameArray(Sel) Then
                PointerA = StudentNameArray.Length
                txtResult.Text = "The ID is: " & StudentIDArray(Sel)
                test = True
            End If
        End If


        If radID.Checked = True Then
            If txtInput.Text = StudentIDArray(Sel) Then
                Dim idNum As Integer
                Dim pos1 As Integer
                Dim pos2 As Integer
                Dim pos3 As Integer
                Dim pos4 As Integer
                Dim pos5 As Integer
                Dim pos6 As Integer
                Dim pos7 As Integer
                Dim subTot As Integer = 0
                Dim m1 As Integer
                idNum = txtInput.Text
                pos1 = (Mid(idNum, 1, 1))
                pos2 = (Mid(idNum, 2, 1))
                pos3 = (Mid(idNum, 3, 1))
                pos4 = (Mid(idNum, 4, 1))
                pos5 = (Mid(idNum, 5, 1))
                pos6 = (Mid(idNum, 6, 1))
                pos6 = pos6 * 2
                pos5 = pos5 * 3
                pos4 = pos4 * 4
                pos3 = pos3 * 5
                pos2 = pos2 * 6
                pos1 = pos1 * 7
                subTot = (pos1 + pos2 + pos3 + pos4 + pos5 + pos5)
                m1 = subTot Mod 11
                m1 = 11 - m1
                pos7 = (Mid(idNum, 7, 1))
                If pos7 <> m1 Then
                    txtResult.Text = "Invalid ID, Select Clear or Exit"

                Else

                    PointerA = StudentIDArray.Length
                    txtResult.Text = "The Name is: " & StudentNameArray(Sel)
                    test = True
                End If

            End If
        End If

        Sel = Sel + 1

    End While
End Sub

Answer 1

您似乎没有得到校验和计算权。

首先，以下一行：

subTot = (pos1 + pos2 + pos3 + pos4 + pos5 + pos5)

应该是：

subTot = (pos1 + pos2 + pos3 + pos4 + pos5 + pos6)

请注意，您有pos5两次而没有pos6。

并且，要使用mod计算校验和，它应该看起来像这样从0到9得到一个数字：

m1 = subTot Mod 10
m1 = 9 - m1

您现有的代码可以生成从1到11而不是0到9的值。

在任何情况下，请尝试使用此代码计算值：

Dim computed = _
    txtInput.Text _
        .ToCharArray() _
        .Select(Function(c, n) (txtInput.Text.Length - n) * (c - "0"c)) _
        .ToArray()

Dim m1 = 9 - (computed.Take(txtInput.Text.Length - 1).Sum() Mod 10)

Dim pos7 = computed.Last()

此代码具有额外的优势，可以使用任何输入数字。

Visual Basic中的循环的一部分不会执行

1 个答案: