测试特定字符的字符串VB.NET

Question

I have a string that has FTP permissions - "LRSDCWAN" Is there a more efficiant way of checking the relevent CheckBox if the string contains the relevant character?

        If reader.Item("home_perm").Contains("L") Then
            CBoxList.Checked = True
        End If
        If reader.Item("home_perm").Contains("R") Then
            CBoxRead.Checked = True
        End If
        If reader.Item("home_perm").Contains("S") Then
            CBoxSubDir.Checked = True
        End If
        If reader.Item("home_perm").Contains("D") Then
            CBoxDelete.Checked = True
        End If
        If reader.Item("home_perm").Contains("C") Then
            CBoxCreate.Checked = True
        End If
        If reader.Item("home_perm").Contains("W") Then
            CBoxWrite.Checked = True
        End If
        If reader.Item("home_perm").Contains("A") Then
            CBoxAppend.Checked = True
        End If
        If reader.Item("home_perm").Contains("N") Then
            CBoxRename.Checked = True
        End If

Thanks.

Answer 1

While it doesn't get rid of your .Contains() problem, you can simplify the logic quite a bit.

If you notice, you are using:

If reader.Item("home_perm").Contains("L") Then
    CBoxList.Checked = True
End If

You can simplify this by just saying

CBoxList.Checked = reader.Item("home_perm").Contains("L")

You can do this for all of your checkboxes. It doesn't solve the needing to call contains, but it eliminates 2/3 of your lines of code.

Answer 2

EDIT.. Doh, I missed the fact that it's a different checkbox for each character.

Okay, in that case I'd use a Dictionary(Of Char, CheckBox) for each character. Something like this - but in less broken VB :)

' Assumes VB10 collection initializers
Dim map As New Dictionary(Of Char, CheckBox) From {
    { "L", CBoxList },
    { "R", CBoxRead },
    { "S", CBoxSubDir },
    { "D", CBoxDelete },
    { "C", CBoxCreate }
}

For Each c As Char In reader.Item("home_perm")
    Dim cb As CheckBox
    If map.TryGetValue(c, cb) Then
        cb.Checked = True
    End If
Next

Answer 3

Regular Expressions.

http://msdn.microsoft.com/en-us/library/hs600312(VS.71).aspx

OR

string.indexof method:

    Dim myString As String = "LRSDCW" 
    Dim myInteger As Integer 
    myInteger = myString.IndexOf("D") // myInteger = 4 
    myInteger = myString.IndexOf("N") // myInteger = -1

Use an Array for myInteger and check each member of the array for a value other than -1, if it is -1, don't check the box.

Answer 4

您能否将所有比较值放入通用列表中并遍历该列表？

Answer 5

CBoxRename.Checked = (New Regex("[LRSDCWAN]").Match(reader.Item("home_perm")).Count > 0) ?

这是非常低效的-每次都是相对密集类的全新实例，因此您可以缓存一个实例并在需要时重用它，但是这样可以使它整齐地适合一行。