regex vb.net ismatch always return true

Question

am trying to implement validations using regex

The validation in aspx page works fine

<asp:RegularExpressionValidator ID="regexEmailValid" display="none" runat="server" ValidationExpression="(([a-z]|[A-Z]|[0-9]|[ ]|[-]|[_]|[@]|[.]|[!]|[$])*)*" ControlToValidate="txtUser" ErrorMessage="Invalid User Name Format"></asp:RegularExpressionValidator>

same one in code behind always returns true

Regex.IsMatch(UserName, "(([a-z]|[A-Z]|[0-9]|[ ]|[-]|[_]|[@]|[.]|[!]|[$])*)*")

tried adding ^ to start but still it always returns true

Regex.IsMatch(UserName, "^(([a-z]|[A-Z]|[0-9]|[ ]|[-]|[_]|[@]|[.]|[!]|[$])*)*")

What am i doing wrong ?

On what input string? * means zero too so this always match. — revo
– revo, Commented May 10, 2018 at 20:02
@revo thank you will try this am not so good at regex : ) i think i missed the $ for end of string..but your looks short and sweet :) — Peru
– Peru, Commented May 10, 2018 at 20:08

revo · Accepted Answer · 2018-05-10 20:11:21Z

1

You are misusing alternations and capturing groups while you could have all those character classes into one. You also have * as quantifier which means zero or more. So regardless of anchors it matches. Your solution would be:

^[a-zA-Z0-9 _@.!$-]+$

answered May 10, 2018 at 20:11

revo

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4 Comments

Peru Over a year ago

can these include character in any order in case i need to add remove in feature ?

revo Over a year ago

Order doesn't matter. But some special characters like - and ^ should be escaped or treated carefully.

Peru Over a year ago

i noticed - at the end...what should i change if i should allow ^ in to my current regex ?

revo Over a year ago

^ has a special meaning when is used as first char in a character class. So avoid using it there if you mean a literal ^. A safe way would be escaping. With escaping \^ it doesn't matter where it resides.

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