A colon cannot be used in the ID of a .NET control. I quote from the following website: http://msdn.microsoft.com/en-us/library/system.web.ui.control.id.aspx
"Only combinations of alphanumeric characters and the underscore character ( _ ) are valid values for this property. Including spaces or other invalid characters will cause an ASP.NET page parser error."
Is there a reason why alphanumeric characters have to be used?
Easy to find on MSN...
Only combinations of alphanumeric characters and the underscore character ( _ ) are valid values for this property. Including spaces or other invalid characters will cause an ASP.NET page parser error.
As for why, I cannot give an answer, other than it makes sense to me as a developer that you never use anything other than alphanumerics and underscores for variable names. There's no obvious reason why that should not extend to control IDs as well.
Related
I have the following validation expresion on an asp.net web form that allows alphanumeric characters, spaces,at least one alpha character, and a minimum of 3 characters and a maximum of 20:
ValidationExpression="(?!^[0-9]$)(?!^[a-zA-Z]$)^([a-zA-Z0-9 _]{3,20})$"
Now I have been asked to allow hyphens and apostraphes but no other special characters.
How can I implement this in my current validation?
This (?!^[0-9'-]$)(?!^[a-zA-Z'-]$)^([a-zA-Z0-9 _'-]{3,20})$?
Well, the main trick here is that - sign should be placed at the end of the character group for it to be parsed as a literal hyphen.
Try this:
(?=.*?[A-Za-z]+)^[a-zA-Z0-9_\-' ]{3,20}$
In my requirement a Textbox should allow Alphabets,Numeric s, Special Characters,Special Symbols With at least one Alphabet.
I will try like this but i am not getting.
^\d*[a-zA-Z][a-zA-Z0-9#*,$._&% -!><^#]*$
You may want to have 2 regular expression validators; one for validating the allowed characters, and one for validating that at least on alphabet has been provided. You may be able to get at least one, but this way, you can have two separate validation messages to show the user explaining why the input is wrong.
Just match for special characters until you encounter a letter, then match for everything until the end of the string:
^[0-9#*,$._&% -!><^#]*[a-zA-Z0-9#*,$._&% -!><^#]*$
Use lookaheads :
/^(?=.*[a-zA-Z])[\w#*,$.&%!><^#-]*$/
Edit :
I assume the - is meant as the actual - character and not a range of space to !.
I removed the space character. You can of course add it if you want.
[ -!]
Effectively means :
[ -!] # Match a single character in the range between “ ” and “!”
And I have no idea what that range entails!
I created the register form in asp.net. And I want to validate Name. This is not included special characters especially '#' character. I used a regular expression validator. I wrote in ValidationExpression that is ^[A-Za-z0-9.'-_\s]+$. It is OK special characters exact '#' character. How to correct regexp. Please help me.
'-_ means every character between ' and _, which includes a large number of characters.
You should escape the - by writing \-.
Using ASP.NET syntax for the RegularExpressionValidator control, how do you specify restriction of two consecutive characters, say character 'x'?
You can provide a regex like the following:
(\\w)\\1+
(\\w) will match any word character, and \\1+ will match whatever character was matched with (\\w).
I do not have access to asp.net at the moment, but take this console app as an example:
Console.WriteLine(regex.IsMatch("hello") ? "Not valid" : "Valid"); // Hello contains to consecutive l:s, hence not valid
Console.WriteLine(regex.IsMatch("Bar") ? "Not valid" : "Valid"); // Bar does not contain any consecutive characters, so it's valid
Alexn is right, this is the way you match consecutive characters with a regex, i.e. (a)\1 matches aa.
However, I think this is a case of everything looking like a nail when you're holding a hammer. I would not use regex to validate this input. Rather, I suggest validating this in code (just looping through the string, comparing str[i] and str[i-1], checking for this condition).
This should work:
^((?<char>\w)(?!\k<char>))*$
It matches abc, but not abbc.
The key is to use so called "zero-width negative lookahead assertion" (syntax: (?! subexpression)).
Here we make sure that a group matched with (?<char>\w) is not followed by itself (expressed with (?!\k<char>)).
Note that \w can be replaced with any valid set of characters (\w does not match white-spaces characters).
You can also do it without named group (note that the referenced group has number 2):
^((\w)(?!\2))*$
And its important to start with ^ and end with $ to match the whole text.
If you want to only exclude text with consecutive x characters, you may use this
^((?<char>x)(?!\k<char>)|[^x\W])*$
or without backreferences
^(x(?!x)|[^x\W])*$
All syntax elements for .NET Framework Regular Expressions are explained here.
You can use a regex to validate what's wrong as well as what's right of course. The regex (.)\1 will match any two consecutive characters, so you can just reject any input that gives an IsValid result to that. If this is the only validation you need, I think this way is far easier than trying to come up with a regex to validate correct input instead.
So, I basically would like to test to see if a string contains a range of alphanumeric characters. It's to be used as a client-side validation and I don't want to prevent users from entering whatever they want. Best to give examples of what should/should not pass validation:
So to be specific, the expression I'm looking for is to test to make sure string contains anywhere from 3 to 10 alphanumeric characters. I'd like to plug into an ASP.NET client side validator.
NOTE: quotes not part of input (but could be!)
" f o o " should pass since there are 3 chars
"f_0_0" should pass
" fo " should not
"F......o......o......b.....a......r" should pass
thx
^([^a-zA-Z0-9]*[a-zA-Z0-9][^a-zA-Z0-9]*){3,10}$
Allows for exactly 3-10 alphanumeric characters, each surrounded by an arbitrary number of non-alphanumeric characters.
(Untested, but it should conform to the JScript subset of the standard .net Regex syntax, as required by the RegularExpressionValidator. Unfortunately, the shorthands \w and \W cannot be used since they include the underscore as an alphanumeric character.)
I'm not familiar with ASP.NET client-side validators, so I'm not sure if you need to do this in a regex, but potentially an easy solution is as follows:
Remove all non-alphanumeric characters (regex replace [^0-9A-Za-z] with nothing).
Check if string length is 3 or greater.