Hi RegEx experts

 I have the requirements as below to create a regex for my application.

The string should not have the following

1) Space should not be allowed

2) <any text> should not be allowed

3) <! should not be allowed

4) &# should not be allowed

5) script: should not be allowed

6) expression( should not be allowed

7) " on... =" should not be allowed (on preceded by a space, followed by alpha characters and spaces and followed by =)

I will appreciate your help deeply from the bottm of my heart. My head is spinning trying to figure out all the commands and fitting all the above requirements above together. I know someone is out there for which it is a piece of cake.

Sincerely

-Arun

What regex engine are you using?  By space do you mean just the " " space character or do you mean any whitespace character?  You want to allow !> but not <! ?  It might also be best if you provide a real text example of what might be submitted and what you don't want.

---

Hi ddrudik

Thanks for your reply. All your questions are valid. Below is the answers as I know it.

1) Space is a white space only " "

2) Yes, allow !> but do not allow <!

3) It should not allow "" (quotes) also

4) It should not allow | (pipe) also

Example.

The string xxx<xxx>xx not allowed

The string xxxscript:xx not allowed

the string xxx xxx not allowed

the string xxx<xxx xxx>xxx not allowed

the string xxx|xxx not allowed

the string xxx<!xxx not allowed

the string xxxexpression(xxx not allowed

the string xxx onxxx= xxx not allowed

Hope it helps

Thanks for your help again

Regards

-Arun

 

You should be able to regex test operation with (note any match is to be considered a string that is not allowed):

(?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=))

---

Hi

I know you asked me the question what engine? I am using .NET engine.

When I try your regex below, I get the following error.Is it because of .NET engine?

------------------------------------------------------------------ 

There was an error in the regular expression!

parsing "(?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=))" - Not enough )'s.

Parameter name: (?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=))

------------------------------------------------------------------ 

What am I missing?

Thanks

-Arun

 

VB or C#?

---

C#

http://pastebin.com/f5e5a851d

---

hi ddrudik

Thankyou so much. It works!!!!

Please send me your address. I would like to send you a small token of appreciation. I needed help and you have been my saviour.

Best Regards

-Arun

Your words of appreciation are enough payment for me, thanks though.  If you need another regex solution in the future feel free to stop back to this forum anytime.

---

Hi Doug

I do not have to refer you as ddrudik since I looked at your profile and found your real name. Sorry for refering to you as ddrudik earlier!!!

I have few related questions to this regex. I am trying to understand the basics of this regex string so that I can create some variations myself without bugging you all the time. The string you gave is as follows.

(?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:| on[a-z]+=))

Can you please explain me the basics of the string above? Specifically my questions are as below

Q1) (?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:| on[a-z]+=)) - The bolded sequence ["| ] restricts the character " (quote) or | (pipe) or space from the string right? That means if I have to create a regex which needs to restrict only " (quote) and | (pipe) then I can change the regex to (?=.*["|]|(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=)) and it will work right?

Q2) If I do not need to restrict any of these characters (" (quote) or | (pipe) or space) , can I change the regex to (?=.*[]|(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=)) or there is a better way?

Q3) (?=.*["| ]|(?:<!|expression\(|<[^>]*>|&#|script:| on[a-z]+=)) - The bolded sequence is restricting the special sequences like <> etc right. Looking at the .net help, (?: matches pattern without capturing it. Just for my understanding, can we include the restrictions mentioned in Q1 as part of this sequence (?: and make it simple. Why we have 2 separate sections in the regex to restrict the characters in Q1 and character sequences like <> etc.

Q4) I have an existing regex for email addresses as follows. ^(?=.*@.*\.)(?!.*@.*@)(?!.*[/|\\;,<>\s]).+$. I need to modify this regex to restrict all the special sequences being referred in Q3 above. (<!, &#, script:, expression(, " on... ="). Please help me with this.

I know these are lot of questions. I do not have words to appreciate your help in this. The reason for questions Q1 - Q3 is so that I can learn this a little better and I can make some variations on my own. 

 Regards and thanks in advance

-Arun

 

Q1:Yes.

Q2:(?=.*(?:<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=))

Q3:(?=.*(?:["| ]|<!|expression\(|<[^>]*>|&#|script:|on[a-z]+=))

Q4:^(?=.*@.*\.)(?!.*(?:.*@.*@|[/"|\\;,\s<>]|expression\(|&#|script:|on[a-z]+=)).+$ with the extra items removed/combined, although since you disallow <> with the rule, the script, on...= are all probably extra to the pattern since they wouldn't be useful without an HTML tag of some sort <>.

---

Thanks Again for your help.

-Arun