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我正在为我的学校课程构建一个计算项目，并且我有一个相当大的if声明。当我运行程序时，它一点也不慢，但我只是想知道写大if语句是否被认为是不好的。

    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
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3 回答 3

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它很难阅读，但适当的缩进可以缓解这种情况。这也可能表明您的代码需要进行一些重构。例如，很长的if语句可以这样写：

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

    ...

}

此外，请务必利用短路的布尔语句并将最容易评估的表达式放在首位。

于 2013-03-20T19:56:18.917 回答
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

当你这样做时寻找简化的事情你的代码没有做任何事情，除非 strComputerRoom(BookingNumber) = strCR.

这看起来没什么大不了的，但如果你开始砍掉这样的东西，你就会得到真正的东西。

注意可能已经填满了 VB，因为我是一个 C# 男孩，我会让你填写它的其余部分......我我会把这些单选按钮放在一个数组中，然后它就只是一个改变所有 if 和 elseing 的问题，以便在你对它们进行 sussed 之后提出循环的开始和结束之类的东西。

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

看着它，你可以从几行数学开始计算。不过可能会挑战你的老师，我不知道你的距离有多远。当你在大约五行代码中给出这个时，他们可能会怀疑，如果我为你做，你就不会学习 nuffin'。

程序员规则 #21 - 我们不喜欢大量打字。

于 2013-03-20T20:46:43.840 回答
0

更新

我收回它，你可以用这个替换你的所有代码：

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

大量的 if 块非常不受欢迎。一般来说，如果可能的话，最好将它们排除在外。例如，你会经常看到类似的东西

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

不久前我问了一个类似（不一样）的问题，得到了这个非常有用的答案：
https ://softwareengineering.stackexchange.com/a/174977/57863

链接到：
https ://softwareengineering.stackexchange.com/a/172910/57863

提供了一些关于重构主题的重要链接。

于 2013-03-20T21:41:42.697 回答