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Winform filter text in a textbox

Posted on 2007-12-03
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Last Modified: 2013-12-16
Hi all,

I want Skip . ,  : , ;  and Numbers when a key on a textbox. Also Is it poosible to change small letters to Caps as I key.I did the below to skip numbers but other characters I am not able to skip.

 private void txtInitials_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar))
            {
                               

              //do nuthing
            }
            else
            {
                e.Handled = true;
            }

        }


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Question by:AdibRahman77
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12 Comments
 
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Assisted Solution

by:evilrix
evilrix earned 800 total points
ID: 20399070
Try something like this: -
            string sSkip = @"[^\.,:;]";
            Match m = Regex.Match(e.KeyChar.ToString(), sSkip);
            if (m.Success)
            {
                e.Handled = true;
            }

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Expert Comment

by:evilrix
ID: 20399075
The regular expression will only be true (m.Success) if it cannot find any of the chars you specified. NB. it is necessary to escape the . as it is a special char in a regex.

More info on regexes...

http://www.regular-expressions.info/
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20399080
try with:

            if (!char.IsDigit(e.KeyChar) && !char.IsPunctuation(e.KeyChar))
            {
              //do nuthing
            }
            else
            {
                e.KeyChar = char.ToUpper(e.KeyChar);
                e.Handled = true;
            }

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LVL 40

Expert Comment

by:evilrix
ID: 20399108
BTW: if you include \d in you regex it will also filter out numbers: -
string sSkip = @"[^\d\.,:;]";

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Expert Comment

by:evilrix
ID: 20399124
>> char.IsPunctuation(e.KeyChar)

Won't that also include other punctuation chars that are not listed (which may or may not be desirable)?

http://msdn2.microsoft.com/en-us/library/6w3ahtyy.aspx

Valid punctuation marks are members of the following categories in UnicodeCategory: -

   ConnectorPunctuation
   DashPunctuation
   OpenPunctuation
   ClosePunctuation
   InititalQuotePunctuation
   FinalQuotePunctuation
   OtherPunctuation.
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LVL 55

Accepted Solution

by:
Jaime Olivares earned 1200 total points
ID: 20399134
I think regex is too much complex and unnecessary, string.IndexOf() will do the job faster.

if ( ".,:;".IndexOf(e.KeyChar) >= 0)
{
    // do anything
}
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Expert Comment

by:Jaime Olivares
ID: 20399149
In fact you can check for valid characters instead of invalid, in this case I think would be simpler.
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Expert Comment

by:evilrix
ID: 20399151
>> I think regex is too much complex
I guess that all depends on whether you think a regex is complex or not :)
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Expert Comment

by:Jaime Olivares
ID: 20399431
it is complex for a beginner user that just want to detect ONE character in a list of characters, with no kind of complex needs like specific character/word sequencing. All this besides the fact that regex is usually has slower performance than other alternatives.

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Expert Comment

by:evilrix
ID: 20399477
>> it is complex for a beginner user that just want to detect ONE character in a list of characters, with no kind of complex needs like specific character/word sequencing
So I shouldn't offer it as an option? It's a valid way to solve this problem, I think the OP has the right to choose if they wish to use it or not!

>> All this besides the fact that regex is usually has slower performance than other alternatives.
Most modern DFA and NFA regex engines have advanced optimization techniques; however, I agree that for very simple checks an alternative may prove more efficient (but less flexible).
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LVL 55

Expert Comment

by:Jaime Olivares
ID: 20399585
>>So I shouldn't offer it as an option? It's a valid way to solve this problem
It is valid for me to say that it is complex ;)
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LVL 40

Expert Comment

by:evilrix
ID: 20399603
>> It is valid for me to say that it is complex ;)
Yup, but it's also valid for me to point out that's a subjective opinion ;)
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