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Editorial Team
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Asked: 2026-06-13T22:26:42+00:00

There is a long set of characters that are not allowed to validate an

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There is a long set of characters that are not allowed to validate an input box of winform app.

So i figured that rather than making the long list that are not allowed make the shorter one that are allowed.

The set that is allowed are (a-z,A-Z, 0-9,@,.) .Rest every thing that can be entered are not allowed.

This is the regex that i have made for this.

Regex.IsMatch(textBox1.Text, @"[@\.\w]+$")

It seem to work in some cases but when i enter the data in this format normal character or number special character normal character or number it seems to break few example ee(vv, 55)44,aba&3B.

Not able to figure out whats wrong in this.

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1 Answer

  1. Editorial Team

    Your regex is not valid, because you don’t validate all string, but the last part.
    You should start it with ^ – beginning of the line symbol.

    Regex.IsMatch(textBox1.Text, @"^[\w@.]*$")

    \w also means letters in every language, so it will validate the string "абц" too.
    So if you need only for english, use 

    Regex.IsMatch(textBox1.Text, @"^[a-zA-Z0-9@.]*$")
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