How to make a specific regex for C#?

AsleeKaizoku · 04-05-2009, 01:27 AM

Im trying to make a regular expresion which...

1) Consist of at least one non alphanumeric character (not including white spaces)
2) At least 7 characters long

So it would match something like...

Hello!1
P@ssword

but not:

Hello1 1
Password111

Magos · 04-05-2009, 02:50 AM

Alphanumeric characters are "[a-zA-Z0-9]", so non-alphanumeric would be "[^a-zA-Z0-9]".
You don't mention any rules of the oterh characters, so I'll assume almost any can do. This is the pattern ".".
The final expression could then be ".*[^a-zA-Z0-9].*".
Note that * is greedy (look this up!) so you may need to use ".*?" instead of ".*", but I don't think it matters in this case.
As for the length of at least 7 it gets a little trickier. Can't you just check the length in code?

AsleeKaizoku · 04-05-2009, 03:10 AM

Quote:

Originally Posted by Magos

Can't you just check the length in code?

Ahhh! Bloddy hell, why didn't I think of that? That makes it so much easier

Code:

Regex regexPassword = new Regex(@".*[^a-zA-Z0-9].*");
if (!regexPassword.IsMatch(txtPass.Text.ToString().Trim()))
{
  lblError.Text = "&nbsp;&nbsp;* Must have at least 1 non-alphanumeric character";
  lblError.Visible = true;
}
else if (regexPassword.IsMatch(txtPass.Text.ToString().Trim()))
{
  string temp = txtPass.Text.ToString().Trim();
  if (temp.Length < 7)
  {
    lblError.Text = "&nbsp;&nbsp;* Password length minimum: 7.";
    lblError.Visible = true;
  }
}

Thanks a bunch

Magos · 04-05-2009, 03:16 AM

A few notes:

1) your "else if" is unneccessary, just an "else" will do (you perform that check already in the "if")
2) No need to call ToString() on TxtPass.Text, it is already a string

AsleeKaizoku · 04-05-2009, 04:08 AM

Quote:

Originally Posted by Magos

A few notes:

1) your "else if" is unneccessary, just an "else" will do (you perform that check already in the "if")
2) No need to call ToString() on TxtPass.Text, it is already a string

Oh yeah, (1) its a direct snippet from my code so, there are actually a bunch of other else ifs later on.

(2) I keep forgetting that :P

Cat · 04-05-2009, 04:06 PM

You also said you wanted whitespace characters to not count.

I'd do @".*[^a-zA-Z\s\d].*" for your regex. Anything that's not a letter, whitespace, or number.

04-05-2009, 01:27 AM	#1
AsleeKaizoku Registered User Join Date: Jan 2008 Posts: 17	How to make a specific regex for C#? Im trying to make a regular expresion which... 1) Consist of at least one non alphanumeric character (not including white spaces) 2) At least 7 characters long So it would match something like... Hello!1 P@ssword but not: Hello1 1 Password111
AsleeKaizoku is offline

04-05-2009, 02:50 AM	#2
Magos Confused Join Date: Sep 2001 Location: Sweden Posts: 3,125	Alphanumeric characters are "[a-zA-Z0-9]", so non-alphanumeric would be "[^a-zA-Z0-9]". You don't mention any rules of the oterh characters, so I'll assume almost any can do. This is the pattern ".". The final expression could then be ".[^a-zA-Z0-9].". Note that * is greedy (look this up!) so you may need to use ".?" instead of ".", but I don't think it matters in this case. As for the length of at least 7 it gets a little trickier. Can't you just check the length in code? __________________ MagosX.com Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.
Magos is offline

04-05-2009, 03:16 AM	#4
Magos Confused Join Date: Sep 2001 Location: Sweden Posts: 3,125	A few notes: 1) your "else if" is unneccessary, just an "else" will do (you perform that check already in the "if") 2) No need to call ToString() on TxtPass.Text, it is already a string __________________ MagosX.com Give a man a fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.
Magos is offline

04-05-2009, 04:06 PM	#6
Cat Registered User Join Date: May 2003 Posts: 1,199	You also said you wanted whitespace characters to not count. I'd do @".[^a-zA-Z\s\d]." for your regex. Anything that's not a letter, whitespace, or number. __________________ You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.
Cat is offline

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