如果声明很长

时间：2013-03-20 19:53:47

标签： vb.net if-statement

我正在为我的学校课程建立一个计算项目，我有一个相当大的if声明。当我运行程序时它根本不是很慢，但我只是想知道编写大型if语句是否被认为是坏的。

    For BookingNumber = 0 To intBookingCount - 1
            If intStartPeriod(BookingNumber) = 1 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton1.Enabled = False
                If intLength(BookingNumber) = 1 Then
                ElseIf intLength(BookingNumber) = 2 Then
                    radRadioButton2.Enabled = False
                ElseIf intLength(BookingNumber) = 3 Then
                    radRadioButton2.Enabled = False
                    radRadioButton3.Enabled = False
                ElseIf intLength(BookingNumber) = 4 Then
                    radRadioButton2.Enabled = False
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                ElseIf intLength(BookingNumber) = 5 Then
                    radRadioButton2.Enabled = False
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                ElseIf intLength(BookingNumber) = 6 Then
                    radRadioButton2.Enabled = False
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                ElseIf intLength(BookingNumber) = 7 Then
                    radRadioButton2.Enabled = False
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 2 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton2.Enabled = False
                If intLength(BookingNumber) = 2 Then
                    radRadioButton3.Enabled = False
                ElseIf intLength(BookingNumber) = 3 Then
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                ElseIf intLength(BookingNumber) = 4 Then
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                ElseIf intLength(BookingNumber) = 5 Then
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                ElseIf intLength(BookingNumber) = 6 Then
                    radRadioButton3.Enabled = False
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 3 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton3.Enabled = False
                If intLength(BookingNumber) = 2 Then
                    radRadioButton4.Enabled = False
                ElseIf intLength(BookingNumber) = 3 Then
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                ElseIf intLength(BookingNumber) = 4 Then
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                ElseIf intLength(BookingNumber) = 5 Then
                    radRadioButton4.Enabled = False
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 4 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton4.Enabled = False
                If intLength(BookingNumber) = 2 Then
                    radRadioButton5.Enabled = False
                ElseIf intLength(BookingNumber) = 3 Then
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                ElseIf intLength(BookingNumber) = 4 Then
                    radRadioButton5.Enabled = False
                    radRadioButton6.Enabled = False
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 5 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton5.Enabled = False
                If intLength(BookingNumber) = 2 Then
                    radRadioButton6.Enabled = False
                ElseIf intLength(BookingNumber) = 3 Then
                    radRadioButton6.Enabled = False
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 6 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton6.Enabled = False
                If intLength(BookingNumber) = 2 Then
                    radRadioButton7.Enabled = False
                End If
            ElseIf intStartPeriod(BookingNumber) = 7 And strComputerRoom(BookingNumber) = strCR Then
                radRadioButton7.Enabled = False
            End If
        Next
    Next
End Function

3 个答案:

答案 0 :(得分：0)

很难阅读，但适当的缩进可以减轻这种情况。这也可能表明您的代码需要进行一些重构。例如，真正的长if语句可以这样写：

if (condition == A && condition == C 
        && (someCondition >= 1000 || someOtherCondition != C) 
        || someThirdCondition == D) {

    ...

}

另外，一定要利用短路的布尔语句，并最简单地评估表达式。

答案 1 :(得分：0)

For BookingNumber = 0 To intBookingCount - 1
  bookingNumberLength = intLength(BookingNumber)
  If strComputerRoom(BookingNumber) = strCR then
    Select Case intStartPeriod(BookingNumber)
      Case 1
        radRadioButton1.Enabled = False
        Select Case bookingNumberLength
          Case 2
            radRadioButton2.Enabled = False
          Case 3
            radRadioButton2.Enabled = False
            radRadioButton3.Enabled = False
          Case 4
            radRadioButton2.Enabled = False
            radRadioButton3.Enabled = False
            radRadioButton4.Enabled = False
          Case 5
            radRadioButton2.Enabled = False
            radRadioButton3.Enabled = False
            radRadioButton4.Enabled = False
            radRadioButton5.Enabled = False
          Case 6
            radRadioButton2.Enabled = False
            radRadioButton3.Enabled = False
            radRadioButton4.Enabled = False
            radRadioButton5.Enabled = False
            radRadioButton6.Enabled = False
          Case 7
            radRadioButton2.Enabled = False
            radRadioButton3.Enabled = False
            radRadioButton4.Enabled = False
            radRadioButton5.Enabled = False
            radRadioButton6.Enabled = False
            radRadioButton7.Enabled = False
         End Select
      Case 2
      Case 3
      Case 4
      Case 5
      Case 6
        radRadioButton6.Enabled = False
        If intLength(BookingNumber) = 2 Then
          radRadioButton7.Enabled = False
        End If
      Case 7
        radRadioButton7.Enabled = False
    End Select 
  End If
Next

除非strComputerRoom（BookingNumber）= strCR，否则在执行此操作时，请查看简化操作，除非strComputerRoom（BookingNumber）= strCR。

这看起来不是什么大不了的事，但如果你开始砍掉这样的东西，你就会得到很多东西。

注意可能已经填满了VB，因为我是C＃男孩，我会让你填写剩下的... 我将把这些单选按钮放在一个数组中，然后这只是一个改变所有内容的问题，如果还有其他东西，比如循环的开始和结束以及你怀疑它们之后。

For rb = rbStart To rbEnd
  MyButtons[rb].Enabled = False
Next

看着它，你可以开始并使用几行数学。虽然可能会挑战你的老师，但我不知道你有多远。当你在大约五行代码中给出这个时，他们可能会产生怀疑，如果我为你做的话，你就不会学习nuffin。

程序员规则＃21 - 我们不喜欢做很多打字。

答案 2 :(得分：0)

<强>更新

我取回它，您可以用以下代码替换所有代码：

For BookingNumber = 0 To intBookingCount - 1

    If intStartPeriod(BookingNumber) = 1 Then radRadioButton1.Enabled = False
    If intStartPeriod(BookingNumber) = 2 Then radRadioButton2.Enabled = False
    If intStartPeriod(BookingNumber) = 3 Then radRadioButton3.Enabled = False
    If intStartPeriod(BookingNumber) = 4 Then radRadioButton4.Enabled = False
    If intStartPeriod(BookingNumber) = 5 Then radRadioButton5.Enabled = False
    If intStartPeriod(BookingNumber) = 6 Then radRadioButton6.Enabled = False
    If intStartPeriod(BookingNumber) = 7 Then radRadioButton7.Enabled = False

    Dim total = intStartPeriod(BookingNumber) + intLength(BookingNumber)
    If total >= 3 Then radRadioButton2.Enabled = False
    If total >= 4 Then radRadioButton3.Enabled = False
    If total >= 5 Then radRadioButton4.Enabled = False
    If total >= 6 Then radRadioButton5.Enabled = False
    If total >= 7 Then radRadioButton6.Enabled = False
    If total >= 8 Then radRadioButton7.Enabled = False

Next

巨大的if-blocks非常不受欢迎。一般来说，如果可能的话，最好将它们排除在外。例如，您经常会看到

的内容 
Sub DoStuff()
    If conditionA Then
        DoSomeStuff()
        If conditionB Then
            DoMoreStuff()
        End If
    End If
End Sub

这可以重构为：

Sub DoStuff()
    If Not conditionA Then Return

    DoSomeStuff()

    If Not conditionB Then Return

    DoMoreStuff()
End Sub

我回答了一个类似的（不一样的）问题并得到了这个非常有用的答案：
https://softwareengineering.stackexchange.com/a/174977/57863

与之相关：
https://softwareengineering.stackexchange.com/a/172910/57863

关于重构的主题提供了一些很棒的链接。

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