How to allow particular special characters, letters, numbers in text box?

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using regex for avoid some special characters in textbox.

What I have tried:

using regex for this one but how to allow particular special character,letters,numbers?

Posted 28-Sep-16 1:02am

Raja Ganapathy

Updated 28-Sep-16 3:20am

v2

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Suvendu Shekhar Giri 28-Sep-16 7:19am

Share what have you tried so far.

Raja Ganapathy 28-Sep-16 8:26am

if (Regex.IsMatch(text, @"^[a-zA-Z0-9_]+$"))
{
Master.ShowMessage("Enter number correctly", MessageHelper.MessageType.Information);
}

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BillW33 · Answer 1 · 2016-09-28T03:20:00

Something that will help you in general is to learn more about how to use RegEx. A very helpful site is regexlib[^] they have a large library of Regular Expressions. They also have a RegEx tester[^] which is very helpful in testing your RegEx code. Also, as Griff said, Ultrapico's Expresso[^] is a very useful tool for creating regular expressions.

OriginalGriff · Answer 2 · 2016-09-28T01:15:00

Solution 1

Depends on your existing Regex.
For example:

^\d+$

Would allow only numbers.

^[-+]?\d+(\.\d+)?$

Would allow numbers with a decimal point, and an optional leading plus or minus.
To allow or disallow specific characters, we'd need to know what you want to permit - but get a copy of Expresso[^] - it's free, and it examines and generates Regular expressions.
It'll help you design your own to fit your specific needs.

Posted 28-Sep-16 1:15am

OriginalGriff

Updated 28-Sep-16 1:16am

Comments

W∴ Balboos, GHB 28-Sep-16 8:06am

Thanks for Expresso link - I'll be looking into that.

OriginalGriff 28-Sep-16 8:22am

It's a good 'un - I've been using it for a couple of years, and it makes life a whole load easier. It even generates C# / VB code you can copy'n'paste right into your app.

I wish I'd written it! :laugh: