Regular Expression [ RESOLVED ]

[dogboydelta]

I'm trying to add a regular expression that does not match
if the string begins 123. How can I do this? Any other number beginning will
be a match, such as 133, 124, etc.

[mendhak]

[^123] can be used so that if it starts with 123, no match.

[dogboydelta]

That's what I tried first, but [^123] matches not any of the characters, so if the
string starts with a 1, 2 or 3 it will be rejected. The [^...] only matches one character. I need to reject a string that starts exactly 123. If it starts 321 or 132 it should be accepted. I tried [^1][^2][^3] but that didn't work either, as it matches 3 characters, but if any one is out of line it will reject ( ie. 943 would be rejected ).

[mendhak]

Is it always a string of numbers?

[dogboydelta]

yes.

[mendhak]

I'll try to figure out the regex for this, but couldn't you just use a simple string.IndexOf() operation to figure out whether the first three characters are 123?

[Lord_Rat]

(?!123)

[Lord_Rat]

Well, at least that's it in theory but now that I test it - it doesn't seem to work in practice. Gimme a min. I'll get it for you.

[Lord_Rat]

OK, the dot-net syntax is slightly different than I am used to, but here is what it works out to be:

((?!123)\d{3})

[dogboydelta]

Its probably going to be used in a RegularExpressionValidator ( client side ) aspx file, so it pretty much has to be a straight regularexpression, cant use any string methods. I will try that latest regex and see what happens.

[mendhak]

I can't say I'm familiar with ?!, is that effectively the same as ^?

[dogboydelta]

((?!123)\d{3})

I tried this one - its on the right track. It accepted 124 and rejected 123. The problem is it accepted 123456. Any other suggestions?

[mendhak]

Try

^(?!123)\d*$

[Lord_Rat]

OK, I was thinking it was only a three digit field.

What you are looking for then is:

^((?!123)\d*)

Mendhak:
(?! means "check what is coming up next and make sure it does NOT match this pattern"

(^ is not something I am familiar with.

[dogboydelta]

I got it, you have to add the begin match ^ at the beginning ( otherwise you can match "NOT 123" anywhere in the string and it will be a match.

This works:

^((?!123)\d{3})

[Lord_Rat]

All three of us jumped on the answer bandwagon at the same time. =D

[dogboydelta]

Is there an AND in Regular Expressions? What if I want it to not start with 123 and also not start with 789?

[Lord_Rat]

^((?!123)(?!789)\d*)$

[mendhak]

I understand ?! now. I was using ^, which is apparently regular-regular expressions, but .NET probably confuses it with the anchor start of the string, so it expects ?!.

Fuhh....

[Lord_Rat]

Well, ?! is pretty standard really. =)

But hey, Regular Expressions themselves are for people who are nutjobs (like us) to begin with. I mean, look at what we just wrote and the fact is even makes sense to someone...

[dogboydelta]

Now I'm having another problem. ^((?!123)\d{3}) works great when I test it
using the Regex methods in vb, but when I plug it into a regularexpression validator, it rejects any number I type in at all. What's the deal? I'm using ASP.NET 1.1 , is there some compatibility issue?

[Lord_Rat]

No, if there is anything it is the validator itself since to test my regular expressions I use VB.Net 1.1 using a program I wrote myself.

Try taking out the outside set of parens:
^(?!123)\d*$

[dogboydelta]

I have a program too. I try it in the program and it works, then I cut and paste the expression into the web site and it doesn't work - it rejects everything. There are two regularexpression validators on the same textbox, is that a problem? I'm just guessing at this point, I have no idea why it wont work in the Regex Validator.

[dogboydelta]

Oh I just realized - Validators get converted into Javascript, which may be slightly different as far as Regular Expression syntax compared to .NET, isn't that right?

[penagate]

Do you need JS regex code or .NET crap? If the former I can help.

If you just want it to match any string that does not start with "123", something like this shoudl work:

/(^(123))(.*)/

[Lord_Rat]

... or .NET crap? ...

You are on a .Net forum.

Most of us swear by this language. Be careful.

As for the question, there is no difference between the ASP.Net version and the Javascript version.

The "/" that was just presented is part of the Javascript language, not part of the Regular expression.

[Lord_Rat]

For example of what I mean on the javascript argument, try the following:

assert(/^(?!123)\d*$/.test("123456"));

vs.

assert(/^(?!123)\d*$/.test("456123"));

[Lord_Rat]

Forgot that assert is my own function. Here would be the entire code to test:

<script lang="javascript">
function assert(testVal)
{
 if(!testVal) alert("Assert failed!");
}

function A1(){
         assert(/^(?!123)\d*$/.test("123456"));
}

function A2(){
         assert(/^(?!123)\d*$/.test("456123"));
}
</script>
<input type="button" onclick="A1();" value="1" />
<input type="button" onclick="A2();" value="2" />

[dogboydelta]

Ok, here's my regex:

^((?!\s*\(?\s*123)(?!\s*\(?\s*0))

It rejects a string that starts 123 , OR starts 0, and accepts all others. It works when I do it manually, in Javascript and in .NET Regex( ) methods, but when I plug it into a RegularExpressionValidator it rejects ALL strings. Can someone try that - plug it into a regularexpressionvalidator in ASP.NET 1.1 and see if I'm crazy or not?

[dogboydelta]

This is what is in the WebUIValidation, in case it helps:

function RegularExpressionValidatorEvaluateIsValid(val) {
var value = ValidatorGetValue(val.controltovalidate);
if (ValidatorTrim(value).length == 0)
return true;
var rx = new RegExp(val.validationexpression);
var matches = rx.exec(value);
return (matches != null && value == matches[0]);
}

[Lord_Rat]

Try this one:

^\s*(?!123)(?!0)(.*)$

Does that work?

[dogboydelta]

Yes it does. I don't know why the WebUIValidation uses RegExp.exec instead of
RegExp.test, which just returns a true or false. Anyway, works good.

[Lord_Rat]

OK.

One thing I did notice with the expression you pasted before was that it wasn't closed properly. There should have been four ")" at the end.

But glad it works. It might need a set of parens around the \s* part too. I wasn't sure.

Enter a few spaces before your number and then a valid number. If it fails (with a valid number) then that is probably why.

Which would make it:
^(\s*)(?!123)(?!0)(.*)$