[RESOLVED] Ignoe case in message box

[Mallard8]

Below is the code to delete a member from 2 listboxes.
What I want is to have the name that is typed in the message box to match the name in the two listboxes no matter how it is typed in the message box.

    Private Sub btnDeleteMember_Click(sender As Object, e As EventArgs) Handles btnDeleteMember.Click
        Dim delete_member As String = InputBox("Delete Member", "Delete " &
        "Member")
        If delete_member.Length = 0 Then Exit Sub
        ' delete members name.
        lstHidden.Items.Remove(delete_member)
        lstMembers.Items.Remove(delete_member)
    End Sub

[si_the_geek]

Rather than having the user type a value (trying to get the case and spelling correct), it would be simpler for them (and you) to pick the item to delete based on which listbox item is selected, presumably with a MessageBox for confirmation (eg: "Are you sure you want to delete member: [value of selected] ?").

[Mallard8]

Thanks Si,
I agree it would be better to choose the name and delete the selected, unfortunately if you tap a name in the lstMember box it automatically fires it off to lstMat1 when four names are in lstMat1 it fires off to lstMat2 then lstMat3 then lstMat4 after that the names go to lstMain.
I could just have a message box that shows if the name isn't correct with something like 'You must type the name as it appears in the list'
But just wondered if it was possible to go ignore case

[wes4dbt]

If all you want to do is ignore the case then you could loop through the ListBox items.

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim str = InputBox("Delete Member", "Delete Member").Trim
        If str.Length > 0 Then
            For Each itm In Me.ListBox1.Items
                If itm.ToString.ToUpper = str.ToUpper Then
                    Me.ListBox1.Items.Remove(itm)
                    Exit For
                End If
            Next
        End If
    End Sub

[Mallard8]

Thanks Wes,
Not only has it answered the question but I actually understand how it works.

Unfortunately can't leave a rep

[jmcilhinney]

If you want to do a case-insensitive comparison then you should actually do a case-insensitive comparison, not change the case and do a case-sensitive comparison. The String.Equals method allows you to perform an actual case-insensitive comparison.

[Mallard8]

Tried String.equals but it doesn't work. I guess because I'm comparing 2 strings that are not equal.
So what do I need to add that I'm not doing?

        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim

        If strMatch.Length > 0 Then ' check inputbox has text in it
            For Each itm In lstMembers.Items    ' loop through membeslist
                If String.Equals(itm, strMatch) Then  ' if they match 
                    lstMembers.Items.Remove(itm)    ' remove from members list
                    lstHidden.Items.Remove(itm) ' remove from hidden list
                End If
            Next
        End If

[wes4dbt]

I personally have never used this method, in fact I never new it existed. lol

But if you look at the documentation you see this method has various optional parameters.

If String.Equals(itm.ToString, str, StringComparison.CurrentCultureIgnoreCase)

I don't know if this is the best choice for you, I'll let you work that out.

You might want to use "OrdinalIgnoreCase"

[jmcilhinney]

So what do I need to add that I'm not doing?

What you're not doing is paying attention to Intellisense or reading the documentation, both of which would have told you that String.Equals has multiple overloads and what the parameters of those overloads are for. When you want to know something about a type or member, reading the relevant documentation should ALWAYS be your first course of action. Only if you don't find what you need or understand what you find do you then need to look elsewhere.

[Mallard8]

Stayed with ToUpper as I couldn't get String.Equals, String.Compare, StringComparison.CurrentCultureIgnoreCase or OrdinalIgnoreCase to work.

[jmcilhinney]

Stayed with ToUpper as I couldn't get String.Equals, String.Compare, StringComparison.CurrentCultureIgnoreCase or OrdinalIgnoreCase to work.

Then you did it wrong. Maybe, instead of giving up and doing the wrong thing, you should show us what you actually did and we can help you work out what's wrong with it.

[jmcilhinney]

That said, it's rather simple stuff, particularly as wes4dbt has already shown you how.

Module Module1
 
    Sub Main()
        Dim str1 = "Hello World"
        Dim str2 = "hello world"
        Dim str3 = "Goodbye cruel world"
 
        Compare(str1, str1)
        Compare(str1, str2)
        Compare(str1, str3)
        CompareInsensitive(str1, str1)
        CompareInsensitive(str1, str2)
        CompareInsensitive(str1, str3)
 
        Console.ReadLine()
    End Sub
 
    Sub Compare(a As String, b As String)
        If a = b Then
            Console.WriteLine("Compare: '{0}' is equal to '{1}'", a, b)
        Else
            Console.WriteLine("Compare: '{0}' is NOT equal to '{1}'", a, b)
        End If
    End Sub
 
    Sub CompareInsensitive(a As String, b As String)
        If String.Equals(a, b, StringComparison.CurrentCultureIgnoreCase) Then
            Console.WriteLine("CompareInsensitive: '{0}' is equal to '{1}'", a, b)
        Else
            Console.WriteLine("CompareInsensitive: '{0}' is NOT equal to '{1}'", a, b)
        End If
    End Sub
 
End Module

[Mallard8]

I did read lots of information but most of it conflicts with the other depending which 'expert' on which forum you read.
Here's one I tried

    Private Sub btnDeleteMember_Click(sender As Object, e As EventArgs) Handles btnDeleteMember.Click
        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim

        If strMatch.Length > 0 Then ' check inputbox has text in it
            For Each itm In lstMembers.Items    ' loop through membeslist
                If String.Equals(itm.ToString, strMatch, StringComparison.CurrentCultureIgnoreCase) Then  ' if they match 
                    lstMembers.Items.Remove(itm)    ' remove from members list
                    lstHidden.Items.Remove(itm) ' remove from hidden list
                End If
            Next
        End If
    End Sub

Here's the error
System.InvalidOperationException: 'List that this enumerator is bound to has been modified. An enumerator can only be used if the list does not change.'

[Shaggy Hiker]

If ToUpper worked, and the right version of Equals (CurrentCultureIgnoreCase) doesn't work, that would make me a bit nervous, so I'd be wanting to figure out what was different between the two strings. I don't know if it could be an issue, but could this be ASCII vs Unicode?

[Shaggy Hiker]

I did read lots of information but most of it conflicts with the other depending which 'expert' on which forum you read.
Here's one I tried

    Private Sub btnDeleteMember_Click(sender As Object, e As EventArgs) Handles btnDeleteMember.Click
        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim

        If strMatch.Length > 0 Then ' check inputbox has text in it
            For Each itm In lstMembers.Items    ' loop through membeslist
                If String.Equals(itm.ToString, strMatch, StringComparison.CurrentCultureIgnoreCase) Then  ' if they match 
                    lstMembers.Items.Remove(itm)    ' remove from members list
                    lstHidden.Items.Remove(itm) ' remove from hidden list
                End If
            Next
        End If
    End Sub

Here's the error
System.InvalidOperationException: 'List that this enumerator is bound to has been modified. An enumerator can only be used if the list does not change.'

Oh, that's a totally different issue. Ignore my last post.

You can't be doing removes on lists using a For Each. Items are changing positions when you do that. Instead, use a For Next and iterate backwards:

For x = lstMembers.Items.Count-1 To 0 Step -1
If String.Equals(lstMembers.Items(x).ToString, strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match
lstMembers.Items.RemoveAt(x) ' remove from members list
lstHidden.Items.RemoveAt(x) ' remove from hidden list
End If
Next

[Mallard8]

Shaggy, I don't know what it could be, I ain't that clever yet but I do enjoy the challenge of it all.

JMC, will look through waht you have suggested.

[Mallard8]

Shaggy, what you have written now makes sense of the error message and explains why I was getting in such a pickle!
Turning in for the night will try it tomorrow morning and let you know how I get on.

Thank You

[jmcilhinney]

We probably should have picked up that issue from the code in post #7 but, if you don't tell us what error message you get, we may miss things that we are not actually looking for. It's always important that you specify three things: what you're trying to do, how you're trying to do it and what happens when you try. Different error messages mean different issues and thus we'll be looking for different things. Of course, because this issue is unrelated to the comparison method, using ToUpper wouldn't have helped and you'd have got the same error at the same place.

[wes4dbt]

sh,

You can't be doing removes on lists using a For Each. Items are changing positions when you do that. Instead, use a For Next and iterate backwards:

You can if you're only going to be removing one item, then Exit the For loop as I did in my example. I guess maybe it's a good habit to always iterate backwards when your going to remove something. But either way will work for one item.

[Mallard8]

Wes,
Tried what you suggested removing one item then exiting For loop, below is the code and the error.

        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim
        For Each itm In lstMembers.Items
            If String.Equals(lstMembers.Items(itm), strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match
                lstMembers.Items.Remove(itm) ' remove from members list
                lstHidden.Items.Remove(itm) ' remove from hidden list
                Exit For
            End If
        Next

System.InvalidCastException: 'Conversion from string "Jan" to type 'Integer' is not valid.'
Inner Exception
FormatException: Input string was not in a correct format.

When I step in to it the first name in the lstMembers shows Jan the name I'm looking to delete (strMatch) shows mAndY.
So if I'm asking is Jan = mAndY, where does the string to integer come in to it?

[jmcilhinney]

For Each itm In lstMembers.Items
    If String.Equals(lstMembers.Items(itm), strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match

Why are you trying to get the item at index 'itm' when 'itm' isn't an index of an item but an item? You already have the item so you don't need to get the item again by index, especially when you don't actually have an index.

For Each itm In lstMembers.Items
    If String.Equals(itm, strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match

[Mallard8]

JMC,

Why are you trying to get the item at index 'itm' when 'itm' isn't an index of an item but an item?

Because I don't know any better but now you have explained it in your own special way, which always makes me smile. Thank you I can see, what is now, the obvious.
Below are all three that I have tried and which worked, any others wanting to know how to compare strings in a list can see all three in one place.
Thanks to everyone who subscribed to this thread, I have actually learnt a little more of VB.

'case-sensitive comparison
' changing case of both strings to Upper Case (ToUpper) or lower case (ToLower)
        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim
            For Each itm In lstMembers.Items    ' loop through membeslist
                If itm.ToString.ToUpper = strMatch.ToUpper Then 'change both to upper case if they match
                    lstMembers.Items.Remove(itm)    ' remove from members list
                    lstHidden.Items.Remove(itm) ' remove fron hidden list
                    Exit For 'exit the loop
                End If 'if they don't match
            Next 'go again
'-----------------------------------------------------------------------------------------------	
' case-insensitive comparison
' iterating through items in a listbox in reverse
        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim
        For itm = lstMembers.Items.Count - 1 To 0 Step -1 'go through list box in reverse 
            If String.Equals(lstMembers.Items(itm).ToString, strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match
                lstMembers.Items.RemoveAt(itm) ' remove from members list
                lstHidden.Items.RemoveAt(itm) ' remove from hidden list
            End If 'if they don't match
        Next 'go again
'---------------------------------------------------------------------------------------------------
'case-insensitive comparison
'going through items in list box when a match is found exit the loop
        Dim strMatch = InputBox("Delete Member", "Delete Member").Trim
        For Each itm In lstMembers.Items ' go through items in listbox
            If String.Equals(itm, strMatch, StringComparison.CurrentCultureIgnoreCase) Then ' if they match
                lstMembers.Items.Remove(itm) ' remove from members list
                lstHidden.Items.Remove(itm) ' remove from hidden list
                Exit For 'found a match exit the for loop
            End If 'if they don't match
        Next 'go again

[jmcilhinney]

Because I don't know any better

You need to read your code objectively, i.e. ask yourself what each line is doing and why. You should actually say it out loud because, as we know, actually hearing ourselves say something often makes what's wrong with it obvious when it wasn't by just thinking it. That's why we can often solve problems by talking to someone without their saying a word. Speaking out loud helps us organise our thoughts better. Speaking out loud makes it easier to see what code is actually rather than what you intended it to do. If you had read out loud what that code was actually doing then you'd have seen that it didn't really make sense. As you say, it's obvious now that it's been pointed out but reading it out loud for yourself is almost as good.

[Mallard8]

John,
Thank you for the advice, I must admit that is something I've never tried but will give it a go.

Graham

[jmcilhinney]

I must admit that is something I've never tried but will give it a go.

You may be surprised. When we just look, we often see what we expect to see. Even if you read it in your head but read it properly rather than just looking at the words, you'll often see what's actually there when you previously saw what you thought was there. If you read aloud though, you ensure that you don't cheat when reading in your head and get no benefit from it.

[Mallard8]

It would appear similar to 'You can't see the wood for the trees'
I have now posted it in the Application testing forum so I can get feedback on how I've coded it.
Thanks for all your help in this thread and others.