Question

我有一个For Each语句，我希望能够从我的组合框中选择某个选项开始。这可能吗？

For Each cbo As ComboBox In s_combos
        For Each cov As String In s_coverage

            If combo.Name = cbo.Name And combo.SelectedIndex = 0 Then
                If txtNewMoney.Text <> "" And b_isSmoker = False Then
                    CalculateRunningTotal(False, cov, , CKeyValuePair.GetComboBoxSelectedKey(s_applicants(counter), True))
                ElseIf txtNewMoney.Text <> "" And b_isSmoker = True Then
                    CalculateRunningTotal(True, cov, , CKeyValuePair.GetComboBoxSelectedKey(s_applicants(counter), True))
                End If
                counter += 1
                Exit For
            End If
        Next


        If combo.Name = cbo.Name And combo.SelectedIndex = 1 Then
           'If this option is selected, start over in For Each
            counter -= 1
            Dim dec As frmDeclined = New frmDeclined(DirectCast(sender, Control).Name, Me)
            dec.ShowDialog()
        End If
Next

Answer 1

您可以使用plain for循环，并将迭代器设置回它的初始值。你可能最好重组它以提高效率，如果选择了这个选项，第一次有什么点循环吗？

Answer 2

通常认为从循环内部修改For循环的索引是不礼貌的。

一种社会可接受的方法是使用While循环，在循环内增加或重置自变量。

如果您肯定想要使用For ... Each循环，可以在其外部放置一个While循环进行迭代，以有效地重置For。 .. Each循环。在我能想到的几乎所有情况下，这都会不必要地复杂化，我通常不会推荐它。

Answer 3

您可以创建一个标签并将其改为：

GoHere:
For Each cbo As ComboBox In s_combos
        For Each cov As String In s_coverage

            If combo.Name = cbo.Name And combo.SelectedIndex = 0 Then
                If txtNewMoney.Text <> "" And b_isSmoker = False Then
                    CalculateRunningTotal(False, cov, , CKeyValuePair.GetComboBoxSelectedKey(s_applicants(counter), True))
                ElseIf txtNewMoney.Text <> "" And b_isSmoker = True Then
                    CalculateRunningTotal(True, cov, , CKeyValuePair.GetComboBoxSelectedKey(s_applicants(counter), True))
                End If
                counter += 1
                Exit For
            End If
        Next


        If combo.Name = cbo.Name And combo.SelectedIndex = 1 Then
           'If this option is selected, start over in For Each
            counter -= 1
            Dim dec As frmDeclined = New frmDeclined(DirectCast(sender, Control).Name, Me)
            dec.ShowDialog()
            Goto GoHere
        End If
Next

有没有办法重新开始For Each？

3 个答案: