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Replace problem

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This message was discovered on ASPFriends.com 'aspngregexp' list.
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Yannick Smits

Hi,
Why doesn't the following line remove all <link href=....etc> tags from my
inputString?
System.Text.RegularExpressions.Regex.Replace(inputString,@"<link (.*)>","");

Thanks,
Yannick Smits

Reply to this message...

Wayne King

It looks like this would remove *more* than all <link> tags, not less. =
That is, an inputString like this:
abc <link href=3D"foo"> hello bold text goodbye
would become:
abc goodbye

To stop the engine from matching beyond the <link> tag, this is a simple =
pattern attempt, which uses a lazy quantifier:
<link[^>]*?

However, this isn't quite right because an attribute value could contain =
an embedded greater-than. Such as inputString:
abc <link href=3D">" target=3D"foo"> hello
would become:
abc " target=3D"foo"> hello

This pattern will handle embedded greater-thans (spaces added for =
clarity):
<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >
It could be made more efficient (at the expense of readability), but =
should work as-is nonetheless.

To have the engine ignore spaces, uses the IgnorePatternWhitespace =
option, as:
Regex.Replace(
inputString,
@"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >",
"",
RegexOptions.ExplicitCapture |
RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

-Wayne King
This posting is provided "AS IS" with no warranties, and confers no =
rights.

-----Original Message-----
From: Yannick Smits [mailto:Click here to reveal e-mail address]
Sent: Wednesday, February 06, 2002 5:44 PM
To: aspngregexp
Subject: [aspngregexp] Replace problem

Hi,
Why doesn't the following line remove all <link href=3D....etc> tags =
from my
inputString?
System.Text.RegularExpressions.Regex.Replace(inputString,@"<link =
(.*)>","");

Thanks,
Yannick Smits

| [aspngregexp] member Click here to reveal e-mail address =3D YOUR ID
| http://www.asplists.com/asplists/aspngregexp.asp =3D JOIN/QUIT
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Reply to this message...

Ryan Trudelle-Schwarz (VIP)

Why not just use:

"<link(.|\n)*?>"

Won't the lazy qualifier will stop it before it overtakes the first '>'
character?

-----Original Message-----
From: Wayne King [mailto:Click here to reveal e-mail address]

It looks like this would remove *more* than all <link> tags, not less.
That is, an inputString like this:
abc <link href="foo"> hello bold text goodbye
would become:
abc goodbye

To stop the engine from matching beyond the <link> tag, this is a simple
pattern attempt, which uses a lazy quantifier:
<link[^>]*?

However, this isn't quite right because an attribute value could contain
an embedded greater-than. Such as inputString:
abc <link href=">" target="foo"> hello
would become:
abc " target="foo"> hello

This pattern will handle embedded greater-thans (spaces added for
clarity):
<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >
It could be made more efficient (at the expense of readability), but
should work as-is nonetheless.

To have the engine ignore spaces, uses the IgnorePatternWhitespace
option, as:
Regex.Replace(
inputString,
@"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >",
"",
RegexOptions.ExplicitCapture |
RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

-Wayne King
This posting is provided "AS IS" with no warranties, and confers no
rights.

-----Original Message-----
From: Yannick Smits [mailto:Click here to reveal e-mail address]
Sent: Wednesday, February 06, 2002 5:44 PM
To: aspngregexp
Subject: [aspngregexp] Replace problem

Hi,
Why doesn't the following line remove all <link href=....etc> tags from
my
inputString?
System.Text.RegularExpressions.Regex.Replace(inputString,@"<link
(.*)>","");

Thanks,
Yannick Smits

Reply to this message...

Yannick Smits

Hi,
I tried Wayne's and Ryan's solution but both fail. Is there perhaps
something wrong with the way I'm replacing the text? Should I perhaps use
the String.Replace method?
This is what I tried last:
string editString = Regex.Replace(inputString,@"<link[^>]*?","",
RegexOptions.ExplicitCapture | RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

I also tried @"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >", but this gave me a
compiler error.
Thanks,
Yannick Smits

"Wayne King" <Click here to reveal e-mail address> wrote in message
news:585831@aspngregexp...

It looks like this would remove *more* than all <link> tags, not less. That
is, an inputString like this:
abc <link href="foo"> hello bold text goodbye
would become:
abc goodbye

To stop the engine from matching beyond the <link> tag, this is a simple
pattern attempt, which uses a lazy quantifier:
<link[^>]*?

However, this isn't quite right because an attribute value could contain an
embedded greater-than. Such as inputString:
abc <link href=">" target="foo"> hello
would become:
abc " target="foo"> hello

This pattern will handle embedded greater-thans (spaces added for clarity):
<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >
It could be made more efficient (at the expense of readability), but should
work as-is nonetheless.

To have the engine ignore spaces, uses the IgnorePatternWhitespace option,
as:
Regex.Replace(
inputString,
@"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >",
"",
RegexOptions.ExplicitCapture |
RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

-Wayne King
This posting is provided "AS IS" with no warranties, and confers no rights.

-----Original Message-----
From: Yannick Smits [mailto:Click here to reveal e-mail address]
Sent: Wednesday, February 06, 2002 5:44 PM
To: aspngregexp
Subject: [aspngregexp] Replace problem

Hi,
Why doesn't the following line remove all <link href=....etc> tags from my
inputString?
System.Text.RegularExpressions.Regex.Replace(inputString,@"<link (.*)>","");

Thanks,
Yannick Smits

| [aspngregexp] member Click here to reveal e-mail address = YOUR ID
| http://www.asplists.com/asplists/aspngregexp.asp = JOIN/QUIT
| http://www.asplists.com/search = SEARCH Archives

Reply to this message...

Wayne King

My "lazy-quantifier" pattern has a bug -- I sent a follow-up reply, but =
unfortunately it looks like that message vanished into the Ether. Here's =
that fixed pattern (note the trailing greater-than I originally =
omitted):
<link[^>]*?>

In literal strings, the double-quote is the only "special" character -- =
you still have to escape it. The C# literal string
@"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >"
doesn't work because the embedded double-quotes aren't escaped, as:
@"<link ( [^""'>]+ | ""[^""]*"" | '[^']*' )* >"

-----Original Message-----
From: Yannick Smits [mailto:Click here to reveal e-mail address]
Sent: Friday, February 08, 2002 11:02 AM
To: aspngregexp
Subject: [aspngregexp] Re: Replace problem

Hi,
I tried Wayne's and Ryan's solution but both fail. Is there perhaps
something wrong with the way I'm replacing the text? Should I perhaps =
use
the String.Replace method?
This is what I tried last:
string editString =3D Regex.Replace(inputString,@"<link[^>]*?","",
RegexOptions.ExplicitCapture | RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

I also tried @"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >", but this gave =
me a
compiler error.
Thanks,
Yannick Smits

"Wayne King" <Click here to reveal e-mail address> wrote in message
news:585831@aspngregexp...

It looks like this would remove *more* than all <link> tags, not less. =
That
is, an inputString like this:
abc <link href=3D"foo"> hello bold text goodbye
would become:
abc goodbye

To stop the engine from matching beyond the <link> tag, this is a simple
pattern attempt, which uses a lazy quantifier:
<link[^>]*?

However, this isn't quite right because an attribute value could contain =
an
embedded greater-than. Such as inputString:
abc <link href=3D">" target=3D"foo"> hello
would become:
abc " target=3D"foo"> hello

This pattern will handle embedded greater-thans (spaces added for =
clarity):
<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >
It could be made more efficient (at the expense of readability), but =
should
work as-is nonetheless.

To have the engine ignore spaces, uses the IgnorePatternWhitespace =
option,
as:
Regex.Replace(
inputString,
@"<link ( [^"'>]+ | "[^"]*" | '[^']*' )* >",
"",
RegexOptions.ExplicitCapture |
RegexOptions.IgnorePatternWhitespace |
RegexOptions.IgnoreCase);

-Wayne King
This posting is provided "AS IS" with no warranties, and confers no =
rights.

-----Original Message-----
From: Yannick Smits [mailto:Click here to reveal e-mail address]
Sent: Wednesday, February 06, 2002 5:44 PM
To: aspngregexp
Subject: [aspngregexp] Replace problem

Hi,
Why doesn't the following line remove all <link href=3D....etc> tags =
from my
inputString?
System.Text.RegularExpressions.Regex.Replace(inputString,@"<link =
(.*)>","");

Thanks,
Yannick Smits

| [aspngregexp] member Click here to reveal e-mail address =3D YOUR ID
| http://www.asplists.com/asplists/aspngregexp.asp =3D JOIN/QUIT
| http://www.asplists.com/search =3D SEARCH Archives

| [aspngregexp] member Click here to reveal e-mail address =3D YOUR ID
| http://www.asplists.com/asplists/aspngregexp.asp =3D JOIN/QUIT
| http://www.asplists.com/search =3D SEARCH Archives

Reply to this message...

	System.String
	System.Text.RegularExpressions.Regex
	System.Text.RegularExpressions.RegexOptions

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