Regex Help!

[i00]

I have the following regular expression that I am writing ...

<page\s[^>]*?(?<=\s)title\s*?=\s*?(?<tag>'|")(?<Title>.+?)\k<tag>


This gets elements from html like syntax in this case it gets the title value from the page element (will match it to the title group)...

I need to to work in a multitude of situations and it will currently work for the following situations:

<page someproperty="asd" title="hello">
<page someproperty="asd" title="hello">

However I also want it to work when there are NO quotation marks such that:

<page someproperty="asd" title=hello>

Will match too...

I can't for the life of me figure this one out!

Thanks,
Kris

[ident]

Your pattern is different to the actual html? You dont have to be greedy, just as an example

Option Strict On
 
Imports System.Text.RegularExpressions
 
Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim pattern As String = "(?i)(?<=<pag.+title=""?)[a-z]+(?=""?>)"
        Dim items = {"<page someproperty=""asd"" title=""hello"">",
                     "<page someproperty=""asd"" title=hello>"}
 
 
        MessageBox.Show(String.Join(Environment.NewLine,
                                    From item
                                    In items
                                    Select New Regex(pattern).Match(item).Value)
                                )
    End Sub
 
 
 
End Class

actually thinking about that depending how fussy you are you will want a back reference as "hello would match il post back after dinner

[i00]

Your pattern is different to the actual html? You dont have to be greedy, just as an example

...

actually thinking about that depending how fussy you are you will want a back reference as "hello would match il post back after dinner

Thanks for your reply ... just looking @ yours... there seem to be a few issues with it

You have:
(?i)(?<=<pag.+title="?)[a-z]+(?="?>)

This will NOT match:

<page title='hello'>

And will incorrectly match:

<page sometitle="hello"> <- This shouldn't match @ all
<pag title="hello"> <- This shouldn't match @ all
<page title="hello>there">


Regards,
Kris

[AceInfinity]

Perhaps it could be optimized a bit more, but I took what you had and added what was needed...

Sub Main()
   Dim arr As String() = New String() {
      "<page someproperty="""" title=""1"">",
      "<page someproperty=""asd"" title=""2"">",
      "<page someproperty=""asd"" title=3>",
      "<page someproperty=""asd"" title = 4>",
      "<page someproperty=""asd"" title = '5'>",
      "<page someproperty=""asd"" title = ""6"">",
      "<page  title='7'>",
      "<pAGe      TiTlE='8'>"
   }
   For Each s As String In arr
      Console.WriteLine("Matched: ""{0}""", Regex.Match(s, "<page\s[^>]*?(?<=\s)title\s*?=(\s+)?(?<tag>[""']?)(?<Title>.+)\k<tag>>", RegexOptions.IgnoreCase).Groups("Title").Value)
   Next
   Console.ReadKey()
End Sub

I get this as output:

Matched: "1"
Matched: "2"
Matched: "3"
Matched: "4"
Matched: "5"
Matched: "6"
Matched: "7"
Matched: "8"

[i00]

Perhaps it could be optimized a bit more, but I took what you had and added what was needed...
...

I get this as output:
...

A few problems...
Your method also matches:
<page someproperty="asd" title="hello'>
<page someproperty="asd" title='hello">
Which it shouldn't
... also it groups into tag "asd 123" in:
<page someproperty="asd" title=asd 123>
where it should only group "asd"

.. so i still think my original method is the best one yet... shame since it doesn't work without quotes

Kris

[ident]

I matched exactly what i assumed you wnated to m atch. Can you post up all the examples in html you want to match.

[OICU812]

Try this regex:
<page\s[^>]*?(?<=\s)title\s*?=\s*?(?<tag>'|")?(?<Title>[^>"'\s]+)(?:[^>]*)?\k<tag>?

Dim TestRegex As New Regex("<page\s[^>]*?(?<=\s)title\s*?=\s*?(?<tag>'|"")?(?<Title>[^>""'\s]+)(?:[^>]*)?\k<tag>?",
 RegexOptions.IgnoreCase Or RegexOptions.Multiline)

Produces matches on the "Title" group like:

[AceInfinity]

A few problems...
Your method also matches:
<page someproperty="asd" title="hello'>
<page someproperty="asd" title='hello">
Which it shouldn't
... also it groups into tag "asd 123" in:
<page someproperty="asd" title=asd 123>
where it should only group "asd"

.. so i still think my original method is the best one yet... shame since it doesn't work without quotes

Kris

Okay, but the issues you are providing me with as feedback are very biased..

1. I've never even seen html like this:

<page someproperty="asd" title="hello'>

Nor do I think that it is even valid (I'd have to verify)

2.

... also it groups into tag "asd 123" in:
<page someproperty="asd" title=asd 123>
where it should only group "asd"

I could modify that regex to solve both of these however, but it was never part of the original question in my mind...

I went off the examples you gave, and threw in a couple others that I could think of. If you provide a full list of test cases, and what is supposed to match, I think this thread would have better replies for what you're looking for.

How about this regex:

<page.+title(\s+)?=(\s+)?("[\w\s]+"|'[\w\s]+'|\w+)

The portion after "<page.+" accurately matches these:

title=asd
title="1"
title="2"
title=3
title = 4
title = '5'
title = "6 test words"
title='7'
TiTlE='8'

From this:

<page someproperty="asd" title="hello'>
<page someproperty="asd" title='hello">
<page someproperty="asd" lkjsdf=lksjdf title=asd 123 prp=lkj>
<page someproperty="" title="1">
<page someproperty="asd" title="2">
<page someproperty="asd" title=3>
<page someproperty="asd" title = 4>
<page someproperty="asd" title = '5'>
<page someproperty="asd"  someproperty="asd" title = "6 tes lkjt" someproperty="asd">
<page  title='7'>
<pAGe      TiTlE='8'>

Quick and dirty.

[i00]

The following is valid:

<a href="something" alt="Kris' day out">

.. yours would match Kris not Kris' day out

And i need it to match ALL valid possibilities as I am phasing a large variety of web pages

Kris

[AceInfinity]

title(\s+)?=(\s+)?("[\w\s']+"|'[\w\s]+'|\w+)

All I had to do was add a single quote, now it matches.