Regular Expressions Discussion Boards

Re: Regular Expression to allow combination of character with digits only

OriginalGriff28-Feb-13 21:39

28-Feb-13 21:39

This is not a good regex task - it isn't strictly pattern matching, it's a counting job, which regex is pretty bad at.
While you can do it it would be horribly complex, and if you decided at a later date that you wanted to include special characters in there it would be a real PITA to maintain.

Instead, do it in code: Use two regexes - one to return all the digits, and one to return all the alpha characters. You then check that the length of both is greater than zero.

If you get an email telling you that you can catch Swine Flu from tinned pork then just delete it. It's Spam.

Re: Regular Expression to allow combination of character with digits only

Richard Deeming1-Mar-13 1:25

Richard Deeming

1-Mar-13 1:25

Assuming you're using the .NET RegEx class, you can use a zero-width positive lookahead assertion[^]:

^(?=.*?\d)(?=.*?\D)\w{2,}$

This means:

You're matching the entire string - ^ and $
The string must consist of at least two alpha-numeric characters - \w{2,}
The string must contain any number of characters followed by a digit - (?=.*?\d)
The string must contain any number of characters followed by a character that is not a digit - (?=.*?\D)

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

My co-worker came up with a regex that validate dates... and it even validates leap years!

Sentenryu7-Jan-13 5:54

Sentenryu

7-Jan-13 5:54

please, tell me this has a bug:

"^(((0[1-9]|[12]\\d|3[01])\\/(0[13578]|1[02])\\/((19|[2-9]\\d)\\d{2}))|((0[1-9]|[12]\\d|30)\\/(0[13456789]|1[012])\\/((19|[2-9]\\d)\\d{2}))|((0[1-9]|1\\d|2[0-8])\\/02\\/((19|[2-9]\\d)\\d{2}))|(29\\/02\\/((1[6-9]|[2-9]\\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))))$"

I'm brazilian and english (well, human languages in general) aren't my best skill, so, sorry by my english. (if you want we can speak in C# or VB.Net =p)

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

Thomas Daniels12-Jan-13 22:05

Thomas Daniels

12-Jan-13 22:05

That's a very long expression.
This is a shorter expression that validate dates:

^\d{4}[- /.](0?[1-9]|1[0-2])[- /.](0?[1-9]|[12][1-9]|3[01])$

Expresso[^] is a good tool to create regular expressions.

In some cases, my signature will be longer than my message...

ASP

<em style="color:red"> <b>ProgramFOX</b></em>

ProgramFOX

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

Sentenryu13-Jan-13 22:00

Sentenryu

13-Jan-13 22:00

thanks for the reply, we actually found a bug on that expression when entering 01/01/2013 (dd/MM/yyyy), for some reason, this value was rejected...

I'm brazilian and english (well, human languages in general) aren't my best skill, so, sorry by my english. (if you want we can speak in C# or VB.Net =p)

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

Thomas Daniels14-Jan-13 5:48

Thomas Daniels

14-Jan-13 5:48

Sentenryu wrote:
thanks for the reply

You're welcome!

Sentenryu wrote:
dd/MM/yyyy

My expression is for yyyy/MM/dd. An expression for dd/MM/yyyy:

^(0?[1-9]|[12][1-9]|3[01])[- /.](0?[1-9]|1[0-2])[- /.]\d{4}$

In some cases, my signature will be longer than my message...

ASP

<em style="color:red"> <b>ProgramFOX</b></em>

ProgramFOX

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

pt140127-Jan-13 19:29

pt1401

27-Jan-13 19:29

Its much shorter yes, but it's overly simplistic.
It says 31st Feb is a valid date Frown | :(

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

Thomas Daniels28-Jan-13 6:10

Thomas Daniels

28-Jan-13 6:10

There's a difference between a valid date and a valid date format. A regex is good for checking formats, but I don't think it works for checking whether a day exists.

In some cases, my signature will be longer than my message...

ASP

<em style="color:red"> <b>ProgramFOX</b></em>

ProgramFOX

Re: My co-worker came up with a regex that validate dates... and it even validates leap years!

Lutosław4-Jun-13 13:14

Lutosław

4-Jun-13 13:14

Maybe it checks if you have to go to work too. AFAIK 1.1 is work-free.

Greetings - Jacek

Advanced practice on regexp

msoutopico19-Dec-12 8:06

msoutopico

19-Dec-12 8:06

Hi there,

I've just read the great "30 Minute Regex Tutorial", by Jim Hollenhorst. A brilliant piece of writing. Congratulations, Jim. Expresso is also a really superb tool.

I would need to go deeper into the advanced aspects of regexp, such as the examples in Table 6 (Table 6. Everything we left out.) in that tutorial.

I would like to hear some suggestions about what way I can go. Thanks a lot!

Cheers, Manuel

Re: Advanced practice on regexp

Peter_in_278019-Dec-12 12:04

Peter_in_2780

19-Dec-12 12:04

msoutopico wrote:
Expresso is also a really superb tool.

Yes, indeed it is.

The best suggestion I have is to find (or invent) some interesting problems, then play with Expresso to solve them (in as many ways as you can think of).
Having said that, remember that regex is not the universal solution for string processing. There are many cases where regex is not the appropriate tool.
(Remember the old saw "When all you have is a hammer, everything looks like a nail." Don't let regex become your hammer.)

Cheers,
Peter

Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012

Re: Advanced practice on regexp

msoutopico19-Dec-12 12:54

msoutopico

19-Dec-12 12:54

Thanks Peter.

Any suggestions for regexp advanced exercises?

Peter_in_2780 wrote:
There are many cases where regex is not the appropriate tool.

For example?

I would depend on the case, I suppose.

Cheers, Manuel

how to make a white space regex

shaikh-adil17-Nov-12 23:34

shaikh-adil

17-Nov-12 23:34

sir
i am doing a project, i want to match a string with regex which will match the whole string and it dosent allow two white spaces concerrently on after the other and also it dosent allow white spaces at starting and ending of string, any number of white spaces is allowable but not concurrently one after the other

Re: how to make a white space regex

Peter_in_278018-Nov-12 10:47

Peter_in_2780

18-Nov-12 10:47

I'm not going to write it out for you, but how about

[beginning of string][whitespace] OR [whitespace](two or more) OR [whitespace][end of string]

Any match and it's bad.
Or, depending on how you want to use it, you can invert the test.

Peter

Software rusts. Simon Stephenson, ca 1994. So does this signature. me, 2012

Re: how to make a white space regex

shaikh-adil18-Nov-12 17:39

shaikh-adil

18-Nov-12 17:39

i didint get what you have told

Re: how to make a white space regex

Jochen Arndt18-Nov-12 21:32

Jochen Arndt

18-Nov-12 21:32

He tried to re-define your problem so that it can be easily translated to regular expressions:

Quote:
[beginning of string][whitespace] OR [whitespace](two or more) OR [whitespace][end of string]

He wanted you to write it out yourself. However, I will guide you to the solution. Using Peter's suggestion, you will get:

^\s OR \s{2,} OR \s$

In Perl, this may look like:

PERL

if ($str =~ /^\s/ || $str =~ /\s{2,}/ || $str =~ /\s$/) {
    print "String '$str' contains invalid white space sequence(s).";
}

part of string before a match

PozzaVecia29-Oct-12 10:21

PozzaVecia

29-Oct-12 10:21

I have a path and I want to get the part of a path before my match:

string s1= @"c:\temp\lev1\lev2\lev3\MYWORD\lev5\lev6";
string mtch ="MYWORD"

knowing

s1

and

mtch

I want to get the part of path before mtch, so @"c:\temp\lev1\lev2\lev3\".

I tried with RegEx but I don't know how to be elegant.. I'm only able to find MYWORD position and then use the substring.
Is there a smarter solution?

Re: part of string before a match

Richard Deeming29-Oct-12 10:37

Richard Deeming

29-Oct-12 10:37

Regex seems overkill for this, but you can do it with a zero-width positive lookahead assertion[^]:

string s1 = @"c:\temp\lev1\lev2\lev3\MYWORD\lev5\lev6";
string mtch = "MYWORD";

string pattern = "^.*(?=" + Regex.Escape(mtch) + ")";
// == "^.*(?=MYWORD)"

Console.WriteLine(Regex.Match(s1, pattern).Value);

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: part of string before a match

PozzaVecia29-Oct-12 11:08

PozzaVecia

29-Oct-12 11:08

thanks again

Re: part of string before a match

Matt T Heffron29-Oct-12 11:22

Matt T Heffron

29-Oct-12 11:22

Also look at the various overloads of Regex.Split(), especially if the initial "match" is more than just a simple string.

Regex getting special caracter

PozzaVecia28-Oct-12 4:46

PozzaVecia

28-Oct-12 4:46

I have a string like:

string s1 = "dog().Cat(\"Happy\")";

I want to:
1) count the number of round brackets '(', I expect as result 2
2) get the text inside, I expect "\"Happy"\", which appear in console output as "Happy"
No idea for 1. I try the following for 2

string k = Regex.Match(s1,@"\((\w+)\)").Groups[1].Value;

But It fails in understanding the \" character
Any Idea?

Re: Regex getting special caracter

Richard Deeming29-Oct-12 2:24

Richard Deeming

29-Oct-12 2:24

You're nearly there:

string k = Regex.Match(s1, @"\(""(\w+)""\)").Groups[1].Value;

For #1, unless you need to ensure that the brackets are balanced, Regex is overkill. Add using System.Linq; to your file, and try:

int count = s1.Count(c => c == '(');

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Re: Regex getting special caracter

PozzaVecia29-Oct-12 9:47

PozzaVecia

29-Oct-12 9:47

Thanks you get the point.

Extract tag within pre tag

DATHeike2-Oct-12 0:00

DATHeike

2-Oct-12 0:00

Hi,
I'm going nuts. I've got heaps of html-pages, that have to be adjusted, since there are "a href" tags within "pre" "/pre" code, that have to be removed. Some code like this:

XML

<pre class="brush:xml;toolbar:false;gutter:true;">&lt;constructiongroups xmlns:xsd=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;<br>
 xsd:noNamespaceSchemaLocation=&quot;svgdescription.xsd&quot;&gt;<br>
    &lt;constructiongroup&gt;<br>
        &lt;fza&gt;5&lt;/fza&gt;<br>
        &lt;<a title="HST" href="1802.htm#o2441">hst</a>&gt;10&lt;/hst&gt;<br>
        &lt;<a title="HT" href="1802.htm#o2442">ht</a>&gt;30&lt;/ht&gt;<br>

In the meantime I found espresso to work with, but it doesn't satisfy my needs. I found the following regex:

(?:<pre .*\b>)*(?:<a[^>].*href="[0-9]+\.htm\#o[0-9]+"[^>]*>)(?:</a>)(?:</pre)

But it's not the end of the flagpole, but I don't know how to complete it. At the moment the regex is working partialy, but not as a whole.
Can someone help me, PLEASE?
Cheerio,
Heike

modified 2-Oct-12 6:52am.

Re: Extract tag within pre tag

Pete O'Hanlon2-Oct-12 0:16

Pete O'Hanlon

2-Oct-12 0:16

Could you please close the <a>? It's messed up your post.

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