“小问题”选择案例“用法VB 2010 [英] Small Problem in " Select case" Usage VB 2010

问题描述

我想根据案例在第三个文本框中显示结果所以我创建了10个案例



当我调试它时每次只显示第一个案例虽然输出它1， 2,3,4,5,6,7,8,9,10;

I want display result in third text box based on cases so i created 10 cases

when i debugged it displays only first case every time although output it 1,2,3,4,5,6,7,8,9,10;

Dim Rtn As String
        Select Case Rtn
            Case 1
                Lnt = 1
                TextBox3.Text = " Sister"
            Case 2
                Lnt = 2
                TextBox3.Text = "Enemy"
            Case 3
                Lnt = 3
                TextBox3.Text = "Enemy "
            Case 4
                Lnt = 4
                TextBox3.Text = "Enemy"
            Case 5

                Lnt = 5
                TextBox3.Text = "Friend"
            Case 6
                Lnt = 6
                TextBox3.Text = "Marrage "
            Case 7
                Lnt = 7
                TextBox3.Text = "Enemy"
            Case 8
                Lnt = 8
                TextBox3.Text = "Affection"
            Case 9
                Lnt = 9
                TextBox3.Text = "Enemy"
            Case 10
                Lnt = 10
                TextBox3.Text = "Lover "
        End Select
    End Sub
End Class

Rtn将根据指定的值获得1,2,3,4,5,6,7,8,9,10;

等值案件应该出来，但它总是显示第一个案例姐姐做什么不请帮助我>圣诞快乐到所有

The Rtn will get values like 1,2,3,4,5,6,7,8,9,10;
based on this value the specified case should come as out put but it always displaying first case "Sister" What to do No Please help me>Merry Christmas To All

推荐答案

这是原因之一我讨厌自动投射，而更喜欢在C＃中工作，这会引发错误。



当你在rtn中有字符串1,2,3时，尝试将它与一组整数值进行比较，VB自动解析字符串并将其转换为整数值。由于字符串包含一个，，它不是整数的一部分，它会停止解析，并使用它到目前为止已解析的值：1

所以它总是只执行第一个选项。



但是这里有一个更广泛的问题：你假设Select Case将对你的字符串中的每个子元素起作用：它不会，除非你自己提供一个循环：

This is one of the reasons I hate automatic casting and prefer to work in C# where this will throw up an error.

When you have the string "1,2,3" in rtn, and try to compare it against a set of integer values, VB automatically parse the string and converts it to an integer value. Since the string contains a "," which is not a part of an integer, it stops parsing at that, and uses the value it has parsed so far: 1
So it will always only execute the first option.

But there is a wider problem here: you are assuming the Select Case will work on each sub element in your string: it won''t, unless you provide a loop yourself:

Dim rtn As String = "1,2,3,4"
Dim parts As String() = rtn.Split(","C)
For Each s As String In parts
    Select Case s
        Case "1"
            Lnt = 1
            TextBox3.Text = " Sister"
            Exit Select
        ...
    End Select
Next

Dim Rtn As Integer
        Rtn = Val(Lnt.Length)
        Select Case Rtn
            Case 1
                If Lnt = 1 Then
                    TextBox3.Text = " Sister"
                Else
                    If Lnt = 2 Then
                        TextBox3.Text = "Enemy"
                    Else
                        If Lnt = 3 Then
                            TextBox3.Text = "Enemy "
                        Else
                            If Lnt = 4 Then
                                TextBox3.Text = "Enemyes"
                            Else
                                If Lnt = 5 Then
                                    TextBox3.Text = "Friends"
                                Else
                                    If Lnt = 6 Then
                                        TextBox3.Text = "Marriage "
                                    Else
                                        If Lnt = 7 Then
                                            TextBox3.Text = "Enemys"
                                        Else
                                            If Lnt = 8 Then
                                                TextBox3.Text = "Affection"
                                            Else
                                                If Lnt = 9 Then
                                                    TextBox3.Text = "Enemys"
                                                Else
                                                    If Lnt = 10 Then
                                                        TextBox3.Text = "Lovers "
                                                    Else
                                                        If Lnt = 11 Then
                                                            TextBox3.Text = "Lovers"
                                                        Else
                                                            If Lnt = 12 Then
                                                                TextBox3.Text = "Affection"
                                                            End If
                                                        End If
                                                    End If
                                                End If
                                            End If
                                        End If
                                    End If
                                End If
                            End If
                        End If
                    End If
                End If
        End Select
    End Sub

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