Convert javascript regex to asp.net vb

Question

I'm using the following regex to validate an email address text box in javascript:-

var regex = /^[\_]*([a-z0-9]+(\.|\_*)?)+@([a-z][a-z0-9\-]+(\.|\-*\.))+[a-z]{2,6}$/i;

I need to also run it in the back end of the asp.NET(4) VB site to prevent injection.

When I convert it to what I think it should be for .NET and run it in http://myregextester.com/ set to use .NET and VB it passes:-

^[_]*([a-z0-9]+(.|_*)?)+@([a-z][a-z0-9\-]+(.|-*.))+[a-z]{2,6}$

However when I put it in my code it doesn't work:-

If (Not Regex.IsMatch(theEmail, "^[_]*([a-z0-9]+(.|_*)?)+@([a-z][a-z0-9\-]+(.|-*.))+[a-z]{2,6}$")) Then                    
    Return False
Else
    Return True
End If

Any help with the conversion to VB would be appreciated.

Siva Charan · Accepted Answer · 2012-07-02 16:12:49Z

2

Replace \- to -

^[_]*([a-z0-9]+(.|_*)?)+@([a-z][a-z0-9-]+(.|-*.))+[a-z]{2,6}$

And also set RegexOptions.IgnoreCase. Since /i is set.

Here i indicates IgnoreCase.

Your code will be

If (Not Regex.IsMatch(theEmail, "^[_]*([a-z0-9]+(.|_*)?)+@([a-z][a-z0-9-]+(.|-*.))+[a-z]{2,6}$", RegexOptions.IgnoreCase)) Then                    
    Return False
Else
    Return True
End If

answered Jul 2, 2012 at 16:12

Siva Charan

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1 Comment

user557597 Over a year ago

Unescaping - won't make a difference. Adding an ignore case option is good. As it is now, your regex matches somebody@A-B@@google.

user557597 · Accepted Answer · 2012-07-02 16:47:58Z

1

It seems the only difference between the regexes is that the original one uses a literal dot \. whereas the second one uses a dot . metacharacter. The metacharacter will match anything, the literal dot will just match a dot character.

Try puting the escape back on the dot.

Your two regexes,

old

 ^ [\_]* 
 (
      [a-z0-9]+ 
      ( \. | \_* )?
 )+
 @
 (
      [a-z] [a-z0-9\-]+ 
      ( \. | \-*\. )
 )+
 [a-z]{2,6} $

new

 ^ [_]* 
 (
      [a-z0-9]+ 
      ( . | _* )?
 )+
 @
 (
      [a-z] [a-z0-9\-]+ 
      ( . | -*. )
 )+
 [a-z]{2,6} $

answered Jul 2, 2012 at 16:47

user557597

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