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Case insensitive Arraylist.indexof search

P: n/a
I have an arraylist of string values. I would like to search the arraylist
to find the index of a particular string and I would like the search to be
case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the match
and return 0

Is there a way to make this happen?

John
Nov 21 '05 #1
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10 Replies


P: n/a
There is no way i know of that allows you to do a textual compare on
aray objects unfortunatly. You could use the command lcase or ucase to
convert both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would
take a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest) Then
indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:
I have an arraylist of string values. I would like to search the arraylist
to find the index of a particular string and I would like the search to be
case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the match
and return 0

Is there a way to make this happen?

John

Nov 21 '05 #2

P: n/a
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
There is no way i know of that allows you to do a textual compare on
aray objects unfortunatly. You could use the command lcase or ucase to
convert both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would
take a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest) Then
indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:
I have an arraylist of string values. I would like to search the
arraylist to find the index of a particular string and I would like
the search to be case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the
match and return 0

Is there a way to make this happen?

John

Nov 21 '05 #3

P: n/a
If it doesn't mattter that the items are sorted after you've added them you
can use the CaseInsensitiveComparer and binarysearch, but this only works if
you sort the arraylist with the same
Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
binarysearch.

Hth Greetz Peter

Dim arrList As New ArrayList

arrList.Add("One")
arrList.Add("tWo")
arrList.Add("thRee")
arrList.Sort(CaseInsensitiveComparer.Default)
MsgBox(arrList.BinarySearch("three",
CaseInsensitiveComparer.Default))

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning.
"Matt" <ma*****@interactiveideasandsolutions.com> schreef in bericht
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
There is no way i know of that allows you to do a textual compare on
aray objects unfortunatly. You could use the command lcase or ucase to
convert both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would
take a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest) Then indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:
I have an arraylist of string values. I would like to search the
arraylist to find the index of a particular string and I would like
the search to be case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the
match and return 0

Is there a way to make this happen?

John

Nov 21 '05 #4

P: n/a
Hi,

In addition to Peters comments. Option compare text will make all
of your string compares case insensitive.

http://msdn.microsoft.com/library/de...ionCompare.asp

Ken
---------------
"Matt" <ma*****@interactiveideasandsolutions.com> wrote in message
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
There is no way i know of that allows you to do a textual compare on aray
objects unfortunatly. You could use the command lcase or ucase to convert
both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would take
a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest)
Then
indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:
I have an arraylist of string values. I would like to search the
arraylist to find the index of a particular string and I would like the
search to be case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the
match and return 0

Is there a way to make this happen?

John

Nov 21 '05 #5

P: n/a

Thanks, Peter. I didn't think of that.

John

"Peter Proost" <pp*****@nospam.hotmail.com> wrote in message
news:%2******************@TK2MSFTNGP09.phx.gbl...
If it doesn't mattter that the items are sorted after you've added them
you
can use the CaseInsensitiveComparer and binarysearch, but this only works
if
you sort the arraylist with the same
Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
binarysearch.

Hth Greetz Peter

Dim arrList As New ArrayList

arrList.Add("One")
arrList.Add("tWo")
arrList.Add("thRee")
arrList.Sort(CaseInsensitiveComparer.Default)
MsgBox(arrList.BinarySearch("three",
CaseInsensitiveComparer.Default))

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning.
"Matt" <ma*****@interactiveideasandsolutions.com> schreef in bericht
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
> There is no way i know of that allows you to do a textual compare on
> aray objects unfortunatly. You could use the command lcase or ucase to
> convert both strings to lower or upper case before you compare.
>
> example:
>
> dim al as new arraylist
> al.add("one")
> al.add("two")
>
> dim x as integer = al.indexof(lcase("ONE"))
>
> but in this case, if you have al.add("oNe") then i guess it wont work.
> you could always do al.add(lcase("oNe")).
>
> or you could use this simple search pattern instead to overcome that
> problem. hopefully your arraylist isnt too big, otherwise this would
> take a while.
>
> Public al As Collections.ArrayList
> Private obj As Object
> Private strtest As String
> Private indexof As Integer
>
> Public Sub mysub()
> al.Add("hello")
> strtest = "HeLLo"
>
> For Each obj In al
> If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest) Then > indexof = al.IndexOf(obj)
> End If
> Next
> End Sub
>
>
> Please dont hit me if it doesnt work. i havnt tested it!
>
> Hope this helps. Matt
>
> JohnR wrote:
>
>> I have an arraylist of string values. I would like to search the
>> arraylist to find the index of a particular string and I would like
>> the search to be case insensitive.
>>
>> dim al as new arraylist
>> al.add("one")
>> al.add("two")
>>
>> dim x as integer = al.indexof("ONE") I would like this to find the
>> match and return 0
>>
>> Is there a way to make this happen?
>>
>> John
>>


Nov 21 '05 #6

P: n/a
Hi Ken,

I tried option Compare but it didn't work for the IndexOf which gets
evaluated in the object.equals method.

Ron

"Ken Tucker [MVP]" <vb***@bellsouth.net> wrote in message
news:%2***************@TK2MSFTNGP12.phx.gbl...
Hi,

In addition to Peters comments. Option compare text will make all
of your string compares case insensitive.

http://msdn.microsoft.com/library/de...ionCompare.asp

Ken
---------------
"Matt" <ma*****@interactiveideasandsolutions.com> wrote in message
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
There is no way i know of that allows you to do a textual compare on
aray objects unfortunatly. You could use the command lcase or ucase to
convert both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would
take a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest)
Then
indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:

I have an arraylist of string values. I would like to search the
arraylist to find the index of a particular string and I would like the
search to be case insensitive.

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof("ONE") I would like this to find the
match and return 0

Is there a way to make this happen?

John


Nov 21 '05 #7

P: n/a
I learnt something new today! :)

Thanks Peter

Peter Proost wrote:
If it doesn't mattter that the items are sorted after you've added them you
can use the CaseInsensitiveComparer and binarysearch, but this only works if
you sort the arraylist with the same
Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
binarysearch.

Hth Greetz Peter

Dim arrList As New ArrayList

arrList.Add("One")
arrList.Add("tWo")
arrList.Add("thRee")
arrList.Sort(CaseInsensitiveComparer.Default)
MsgBox(arrList.BinarySearch("three",
CaseInsensitiveComparer.Default))

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning.

Nov 21 '05 #8

P: n/a
Just curious as to why you have to sort the arraylist first...trying to learn
all I can and don't undetstand?
--
Dennis in Houston
"Peter Proost" wrote:
If it doesn't mattter that the items are sorted after you've added them you
can use the CaseInsensitiveComparer and binarysearch, but this only works if
you sort the arraylist with the same
Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
binarysearch.

Hth Greetz Peter

Dim arrList As New ArrayList

arrList.Add("One")
arrList.Add("tWo")
arrList.Add("thRee")
arrList.Sort(CaseInsensitiveComparer.Default)
MsgBox(arrList.BinarySearch("three",
CaseInsensitiveComparer.Default))

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning.
"Matt" <ma*****@interactiveideasandsolutions.com> schreef in bericht
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
There is no way i know of that allows you to do a textual compare on
aray objects unfortunatly. You could use the command lcase or ucase to
convert both strings to lower or upper case before you compare.

example:

dim al as new arraylist
al.add("one")
al.add("two")

dim x as integer = al.indexof(lcase("ONE"))

but in this case, if you have al.add("oNe") then i guess it wont work.
you could always do al.add(lcase("oNe")).

or you could use this simple search pattern instead to overcome that
problem. hopefully your arraylist isnt too big, otherwise this would
take a while.

Public al As Collections.ArrayList
Private obj As Object
Private strtest As String
Private indexof As Integer

Public Sub mysub()
al.Add("hello")
strtest = "HeLLo"

For Each obj In al
If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest) Then indexof = al.IndexOf(obj)
End If
Next
End Sub
Please dont hit me if it doesnt work. i havnt tested it!

Hope this helps. Matt

JohnR wrote:

> I have an arraylist of string values. I would like to search the
> arraylist to find the index of a particular string and I would like
> the search to be case insensitive.
>
> dim al as new arraylist
> al.add("one")
> al.add("two")
>
> dim x as integer = al.indexof("ONE") I would like this to find the
> match and return 0
>
> Is there a way to make this happen?
>
> John
>


Nov 21 '05 #9

P: n/a
Hi Dennis, is far as I remember, you have to do it because otherwise you can
get the wrong index returned.
Or as stated in the msdn:

"If comparer is provided, the elements of the ArrayList are compared to the
specified value using the specified IComparer implementation. If the
ArrayList is not already sorted according to the sort order defined by
comparer, the result might be incorrect."

you can try it for yourself, if you remove the
arrList.Sort(CaseInsensitiveComparer.Default) from my small example you
should get the wrong result.

Hth Greetz Peter

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce
bigger and better idiots. So far, the Universe is winning.
"Dennis" <De****@discussions.microsoft.com> schreef in bericht
news:D8**********************************@microsof t.com...
Just curious as to why you have to sort the arraylist first...trying to learn all I can and don't undetstand?
--
Dennis in Houston
"Peter Proost" wrote:
If it doesn't mattter that the items are sorted after you've added them you can use the CaseInsensitiveComparer and binarysearch, but this only works if you sort the arraylist with the same
Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
binarysearch.

Hth Greetz Peter

Dim arrList As New ArrayList

arrList.Add("One")
arrList.Add("tWo")
arrList.Add("thRee")
arrList.Sort(CaseInsensitiveComparer.Default)
MsgBox(arrList.BinarySearch("three",
CaseInsensitiveComparer.Default))

--
Programming today is a race between software engineers striving to build
bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.
"Matt" <ma*****@interactiveideasandsolutions.com> schreef in bericht
news:Ov**************@TK2MSFTNGP12.phx.gbl...
Oops. that loop wont finish when its supposed to.

after the line: indexof = al.IndexOf(obj)
you will to put: exit for
Matt wrote:
> There is no way i know of that allows you to do a textual compare on
> aray objects unfortunatly. You could use the command lcase or ucase to > convert both strings to lower or upper case before you compare.
>
> example:
>
> dim al as new arraylist
> al.add("one")
> al.add("two")
>
> dim x as integer = al.indexof(lcase("ONE"))
>
> but in this case, if you have al.add("oNe") then i guess it wont work. > you could always do al.add(lcase("oNe")).
>
> or you could use this simple search pattern instead to overcome that
> problem. hopefully your arraylist isnt too big, otherwise this would
> take a while.
>
> Public al As Collections.ArrayList
> Private obj As Object
> Private strtest As String
> Private indexof As Integer
>
> Public Sub mysub()
> al.Add("hello")
> strtest = "HeLLo"
>
> For Each obj In al
> If LCase(CStr(al.Item(al.IndexOf(obj)))) = LCase(strtest)
Then
> indexof = al.IndexOf(obj)
> End If
> Next
> End Sub
>
>
> Please dont hit me if it doesnt work. i havnt tested it!
>
> Hope this helps. Matt
>
> JohnR wrote:
>
>> I have an arraylist of string values. I would like to search the
>> arraylist to find the index of a particular string and I would like
>> the search to be case insensitive.
>>
>> dim al as new arraylist
>> al.add("one")
>> al.add("two")
>>
>> dim x as integer = al.indexof("ONE") I would like this to find

the >> match and return 0
>>
>> Is there a way to make this happen?
>>
>> John
>>


Nov 21 '05 #10

P: n/a
Dennis,
Because ArrayList.BinarySearch is only defined on sorted lists.

http://msdn.microsoft.com/library/de...earchTopic.asp

The reason ArrayList.BinarySearch is only defined on sorted lists is because
the Binary Search algorithm is "optimally" defined on sorted lists.

For details on the Binary Search algorithm see:

http://www.nist.gov/dads/HTML/binarySearch.html

http://en.wikipedia.org/wiki/Binary_search

--
Hope this helps
Jay
T.S. Bradley - http://www.tsbradley.net
"Dennis" <De****@discussions.microsoft.com> wrote in message
news:D8**********************************@microsof t.com...
| Just curious as to why you have to sort the arraylist first...trying to
learn
| all I can and don't undetstand?
| --
| Dennis in Houston
|
|
| "Peter Proost" wrote:
|
| > If it doesn't mattter that the items are sorted after you've added them
you
| > can use the CaseInsensitiveComparer and binarysearch, but this only
works if
| > you sort the arraylist with the same
| > Icomparer(CaseInsensitiveComparer.Default) as you want to use for your
| > binarysearch.
| >
| > Hth Greetz Peter
| >
| > Dim arrList As New ArrayList
| >
| > arrList.Add("One")
| > arrList.Add("tWo")
| > arrList.Add("thRee")
| > arrList.Sort(CaseInsensitiveComparer.Default)
| > MsgBox(arrList.BinarySearch("three",
| > CaseInsensitiveComparer.Default))
| >
| > --
| > Programming today is a race between software engineers striving to build
| > bigger and better idiot-proof programs, and the Universe trying to
produce
| > bigger and better idiots. So far, the Universe is winning.
| >
| >
| > "Matt" <ma*****@interactiveideasandsolutions.com> schreef in bericht
| > news:Ov**************@TK2MSFTNGP12.phx.gbl...
| > > Oops. that loop wont finish when its supposed to.
| > >
| > > after the line: indexof = al.IndexOf(obj)
| > > you will to put: exit for
| > >
| > >
| > > Matt wrote:
| > > > There is no way i know of that allows you to do a textual compare on
| > > > aray objects unfortunatly. You could use the command lcase or ucase
to
| > > > convert both strings to lower or upper case before you compare.
| > > >
| > > > example:
| > > >
| > > > dim al as new arraylist
| > > > al.add("one")
| > > > al.add("two")
| > > >
| > > > dim x as integer = al.indexof(lcase("ONE"))
| > > >
| > > > but in this case, if you have al.add("oNe") then i guess it wont
work.
| > > > you could always do al.add(lcase("oNe")).
| > > >
| > > > or you could use this simple search pattern instead to overcome that
| > > > problem. hopefully your arraylist isnt too big, otherwise this would
| > > > take a while.
| > > >
| > > > Public al As Collections.ArrayList
| > > > Private obj As Object
| > > > Private strtest As String
| > > > Private indexof As Integer
| > > >
| > > > Public Sub mysub()
| > > > al.Add("hello")
| > > > strtest = "HeLLo"
| > > >
| > > > For Each obj In al
| > > > If LCase(CStr(al.Item(al.IndexOf(obj)))) =
LCase(strtest)
| > Then
| > > > indexof = al.IndexOf(obj)
| > > > End If
| > > > Next
| > > > End Sub
| > > >
| > > >
| > > > Please dont hit me if it doesnt work. i havnt tested it!
| > > >
| > > > Hope this helps. Matt
| > > >
| > > > JohnR wrote:
| > > >
| > > >> I have an arraylist of string values. I would like to search the
| > > >> arraylist to find the index of a particular string and I would like
| > > >> the search to be case insensitive.
| > > >>
| > > >> dim al as new arraylist
| > > >> al.add("one")
| > > >> al.add("two")
| > > >>
| > > >> dim x as integer = al.indexof("ONE") I would like this to find
the
| > > >> match and return 0
| > > >>
| > > >> Is there a way to make this happen?
| > > >>
| > > >> John
| > > >>
| >
| >
| >
Nov 21 '05 #11

This discussion thread is closed

Replies have been disabled for this discussion.