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From: mp on 23 Sep 2009 12:02

"Peter Duniho" <no.peted.spam(a)no.nwlink.spam.com> wrote in message
news:op.u0o27aapvmc1hu(a)macbook-pro.local...
> On Tue, 22 Sep 2009 13:34:03 -0700, mp <nospam(a)thanks.com> wrote:
>
>> Is there a way to make String.Contains do a case insensitive comparison?
>> like an equivalent of vb6 Option CompareText in a code module?
>
> It is odd that Contains() doesn't include an overload that takes a
> StringComparison value. It's so odd, we only a month ago had this same
> discussion:
> http://groups.google.com/group/microsoft.public.dotnet.languages.csharp/browse_thread/thread/ebc4258ed2c4270f/c48b6c15df01e8bf
>
snip
Thanks for the link, i'll check it out

mark


From: Peter Duniho on 23 Sep 2009 12:48
On Wed, 23 Sep 2009 00:52:01 -0700, Morten Wennevik [C# MVP]
<MortenWennevik(a)hotmail.com> wrote:

> I disagree.

You can disagree all you like. It doesn't undo the documented problem.

It is true that if you can limit the input to ASCII, or some particular
culture, it is possible to get away with using case-conversion. But .NET
operates on Unicode strings, and provides no concise way to represent
those limitations. Furthermore, when you are posting to a public
newsgroup, you have no way to guarantee that code that uses
case-conversion will be used in this limited way even by convention.

It is nearly as easy to do the comparison _correctly_ as it is to do it
incorrectly. It makes no sense to prefer to write the code to do it
incorrectly.

Pete
From: not_a_commie on 23 Sep 2009 12:53
Use the string.Compare or string.Equals static functions.
From: Harlan Messinger on 23 Sep 2009 15:23
Peter Duniho wrote:
> On Wed, 23 Sep 2009 00:52:01 -0700, Morten Wennevik [C# MVP]
> <MortenWennevik(a)hotmail.com> wrote:
>
>> I disagree.
>
> You can disagree all you like. It doesn't undo the documented problem.

It's the same problem no matter how you factor it. In the other thread
you wrote that "It's the fact that no matter what the culture, simply
changing the case of the string and comparing will not necessarily
produce the same results as doing an actual "case insensitive"
comparison for that culture." I don't see that a "case insensitive
comparison" between a target character and a character that has been
read in is different from comparing the target character to both the
read-in character and its alternate-case counterpart.

If you've got input that's permitted to be fuzzy on case, allowing "X"
as well as "x" and "N" instead of "n", then your code is going to have
to be able to figure out that "PORTRAIT" and "pOrTrAiT" and "porTRaIT"
are all the same as "portrait". Whatever comparison you do is going to
incorporate some assumption as to which characters correspond in an
upper- and lower-case relationship, whether you have
s1.ToLower().Contains(s2.ToLower()) or you use a case-insensitive
regular expression or you hard-code a letter-by-letter comparison. You
can't handle every case: your Turk could type "portrait" or "portraıt"
or "PORTRAIT" or "PORTRAİT" into the configuration file. So you have to
make an assumption, and make it explicit what that assumption is, and
then feel free to code against what that assumption is and treat
anything else as an error condition.

Or you can specify that configuration data and user input are going to
be treated as case sensitive and then not worry about case at all.

> It is true that if you can limit the input to ASCII, or some particular
> culture, it is possible to get away with using case-conversion. But
> .NET operates on Unicode strings, and provides no concise way to
> represent those limitations. Furthermore, when you are posting to a
> public newsgroup, you have no way to guarantee that code that uses
> case-conversion will be used in this limited way even by convention.
>
> It is nearly as easy to do the comparison _correctly_ as it is to do it
> incorrectly. It makes no sense to prefer to write the code to do it
> incorrectly.
From: Sreenivas on 24 Sep 2009 00:27
On Sep 23, 10:38 am, "Peter Duniho" <no.peted.s...(a)no.nwlink.spam.com>
wrote:
> On Tue, 22 Sep 2009 22:15:46 -0700, Sreenivas  
>
> <thatiparthysreeni...(a)gmail.com> wrote:
> > I think using RegularExpressions are overkill ,in this case .
> > do in this way,
> > if(line.ToLower().Contains())
> > {
> >     listBox1.Items.Add(line);
> > }
>
> Regex might be a little bit of overkill as compared to the most efficient  
> alternatives, but simply changing the case is a much poorer solution.  
> Please refer to the previous discussion (I provided a link in my other  
> reply to the OP) for details on why.
>
> I would definitely use Regex before I would be willing to simply convert  
> the case.
> Pete

Pete , i have a question. Does RegexOptions.IgnoreCase( in the code
snippet i posted ) guarantee the comparison of all Unicode characters?
What i am asking is , is my code snippet works for all unicode
characters?
Thanks,
Sreenivas Reddy Thatiparthy.

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