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Changing case
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Ollie Cornes

I want to write a regexp that locates matches and then sets the matched
strings to lower case. It looks like on unix boxed there's a method called
lc() to do this. What's the equivalent in the .NET world of regexp?

Ollie
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Scott (VIP)
You can do this with a regexp, but you can also just call the
string.ToLower() method.

[Original message clipped]
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Jason Salas
HI Ollie,

You can use the following method:

yourStringName.ToLower()

HTH,
Jason

----- Original Message -----
From: "Ollie Cornes" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Saturday, March 02, 2002 5:10 AM
Subject: [aspngregexp] Changing case

[Original message clipped]
Reply to this message...
 
    
Ollie Cornes

I know about the ToLower() method, the part that baffled me was the regexp
part of how to move the matching part of a string into lower case. I am a
little unfamiliar with the way .NET does regexp and it's been a long time
since I wrote any regexps. But I figured it out, here's some code to move
opening HTML tags to lower case:

string pattern = @"(<[A-Z,a-z,0-9]*[>,\s])";
string newHtml = Regex.Replace(inputHtml, pattern, new
MatchEvaluator(CapText));

string CapText(Match m)
{
return m.ToString().ToLower();
}

Ollie

----- Original Message -----
From: "Jason Salas" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Friday, March 01, 2002 11:35 PM
Subject: [aspngregexp] Re: Changing case

[Original message clipped]
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Wayne King
You probably don't want the commas within the character classes, and the =
parentheses are superfluous:
string pattern =3D @"<[A-Za-z0-9]+[>\s]";

This pattern may also accomplish the same thing:
string pattern =3D @"<[^>\s]+";

-----Original Message-----
From: Ollie Cornes [mailto:Click here to reveal e-mail address]
Sent: Friday, March 01, 2002 5:00 PM
To: aspngregexp
Subject: [aspngregexp] Re: Changing case

I know about the ToLower() method, the part that baffled me was the =
regexp
part of how to move the matching part of a string into lower case. I am =
a
little unfamiliar with the way .NET does regexp and it's been a long =
time
since I wrote any regexps. But I figured it out, here's some code to =
move
opening HTML tags to lower case:

string pattern =3D @"(<[A-Z,a-z,0-9]*[>,\s])";
string newHtml =3D Regex.Replace(inputHtml, pattern, new
MatchEvaluator(CapText));

string CapText(Match m)
{
return m.ToString().ToLower();
}

Ollie

----- Original Message -----
From: "Jason Salas" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Friday, March 01, 2002 11:35 PM
Subject: [aspngregexp] Re: Changing case

[Original message clipped]
Reply to this message...
 
    
Ollie Cornes

I've spent a little more time with this regexp to match HTML tags and I
discovered that attribute values containing > characters cause my regexp to
fail, plus spaces in attribute caused problems as well. Below is a larger
regexp that I am currently using to match entire HTML tags. It matches a tag
in more detail, looking for a tagname, zero or more attributes (with or
without values) and an optional trailing /

<[a-zA-Z0-9:]+
(
[\s]+[a-zA-Z0-9:]+
(
(=[^\s"<>]+)|
(="[^"]*")|
(='[^']*')|
()
)
)*
[\s]*\/?\s*>

I have yet to see problems, but that's not to say there aren't any. If
anyone has any experiences that suggest problems with this approach, or if
you have seen a regexp that is proven to match HTML tags, I'd appreciate a
nod. I only need it to match the opening tag, so things like </b> are of no
interest, only <b>, <img src="image.gif" alt="> home">, etc.

Thanks for the help Wayne.

Ollie

PS For anyone who needs simpler HTML matching, this seems to work pretty
well <.*?>

----- Original Message -----
From: "Wayne King" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Saturday, March 02, 2002 3:42 AM
Subject: [aspngregexp] Re: Changing case

You probably don't want the commas within the character classes, and the
parentheses are superfluous:
string pattern = @"<[A-Za-z0-9]+[>\s]";

This pattern may also accomplish the same thing:
string pattern = @"<[^>\s]+";

-----Original Message-----
From: Ollie Cornes [mailto:Click here to reveal e-mail address]
Sent: Friday, March 01, 2002 5:00 PM
To: aspngregexp
Subject: [aspngregexp] Re: Changing case

I know about the ToLower() method, the part that baffled me was the regexp
part of how to move the matching part of a string into lower case. I am a
little unfamiliar with the way .NET does regexp and it's been a long time
since I wrote any regexps. But I figured it out, here's some code to move
opening HTML tags to lower case:

string pattern = @"(<[A-Z,a-z,0-9]*[>,\s])";
string newHtml = Regex.Replace(inputHtml, pattern, new
MatchEvaluator(CapText));

string CapText(Match m)
{
return m.ToString().ToLower();
}

Ollie

----- Original Message -----
From: "Jason Salas" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Friday, March 01, 2002 11:35 PM
Subject: [aspngregexp] Re: Changing case

[Original message clipped]

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Wayne King
Capturing groupings are a performance hit, so minimizing the number of =
parentheses could be useful for your pattern.

A couple things that could be missing with your pattern:

(1) It doesn't do the right thing when the attribute value is a =
single-quoted string with an embedded double-quote. Looks like a typo in =
this clause:
[^\s"<>]+
You probably meant:
[^\s"'<>]+

(2) It doesn't permit whitespace around the equal-sign that separates =
attribute from value.

Here's a pattern very similar to yours that uses less grouping, and =
explicitly captures the tag and each attribute and value:
<
(?'Tag'[a-zA-Z0-9:]+) \s*
(
(?'Attr'[a-zA-Z0-9:]+) \s*
(=3D \s*
(?'Value' [^\s"'>]+ | "[^"]*" | '[^']*')
)? \s* #match zero or one Value (per Attr)
)* #match zero or more Attrs
/?>
Use these options with it:
RegexOptions.ExplicitCapture
RegexOptions.IgnorePatternWhitespace
The 'Tag' and 'Attr' explicit-capturing can be removed if you aren't =
interested in extracting those substrings. The 'Value' grouping is =
required, but it doesn't need to be an explicit (named) capture.

One tricky part about extracting captured substrings is that, in the =
case of this pattern, the "Value" capture may not exist for every =
captured "Attr" (because of valueless attributes). Consider this input =
string:
<td nowrap colspan=3D2>

Then, these results are expected:
match.Groups["Attr"].Captures[0].Value =3D=3D> "nowrap"
match.Groups["Attr"].Captures[1].Value =3D=3D> "colspan"

But, this may be less expected:
match.Groups["Value"].Captures.Count =3D=3D> 1
match.Groups["Value"].Captures[0].Value =3D=3D> "2"

That is, the zeroth "Value" capture does not correspond to the zeroth =
"Attr" capture.

If you aren't concerned with capturing the attributes and values, but =
still want to correctly deal with the "nested >" issue, this pattern =
should work:
< (?'Tag'[a-zA-Z0-9:]+)
(?: [^"'>]+ | "[^"]*" | '[^']*' )*
/?>
With these options:
RegexOptions.IgnorePatternWhitespace
RegexOptions.ExplicitCapture
The ExplicitCapture option isn't actually needed because the pattern =
uses (?:)

-Wayne

-----Original Message-----
From: Ollie Cornes [mailto:Click here to reveal e-mail address]
Sent: Tuesday, March 05, 2002 5:05 AM
To: aspngregexp
Subject: [aspngregexp] Re: Changing case

I've spent a little more time with this regexp to match HTML tags and I
discovered that attribute values containing > characters cause my regexp =
to
fail, plus spaces in attribute caused problems as well. Below is a =
larger
regexp that I am currently using to match entire HTML tags. It matches a =
tag
in more detail, looking for a tagname, zero or more attributes (with or
without values) and an optional trailing /

<[a-zA-Z0-9:]+
(
[\s]+[a-zA-Z0-9:]+
(
(=3D[^\s"<>]+)|
(=3D"[^"]*")|
(=3D'[^']*')|
()
)
)*
[\s]*\/?\s*>

I have yet to see problems, but that's not to say there aren't any. If
anyone has any experiences that suggest problems with this approach, or =
if
you have seen a regexp that is proven to match HTML tags, I'd appreciate =
a
nod. I only need it to match the opening tag, so things like </b> are of =
no
interest, only <b>, <img src=3D"image.gif" alt=3D"> home">, etc.

Thanks for the help Wayne.

Ollie

PS For anyone who needs simpler HTML matching, this seems to work pretty
well <.*?>

----- Original Message -----
From: "Wayne King" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Saturday, March 02, 2002 3:42 AM
Subject: [aspngregexp] Re: Changing case

You probably don't want the commas within the character classes, and the
parentheses are superfluous:
string pattern =3D @"<[A-Za-z0-9]+[>\s]";

This pattern may also accomplish the same thing:
string pattern =3D @"<[^>\s]+";

-----Original Message-----
From: Ollie Cornes [mailto:Click here to reveal e-mail address]
Sent: Friday, March 01, 2002 5:00 PM
To: aspngregexp
Subject: [aspngregexp] Re: Changing case

I know about the ToLower() method, the part that baffled me was the =
regexp
part of how to move the matching part of a string into lower case. I am =
a
little unfamiliar with the way .NET does regexp and it's been a long =
time
since I wrote any regexps. But I figured it out, here's some code to =
move
opening HTML tags to lower case:

string pattern =3D @"(<[A-Z,a-z,0-9]*[>,\s])";
string newHtml =3D Regex.Replace(inputHtml, pattern, new
MatchEvaluator(CapText));

string CapText(Match m)
{
return m.ToString().ToLower();
}

Ollie

----- Original Message -----
From: "Jason Salas" <Click here to reveal e-mail address>
To: "aspngregexp" <Click here to reveal e-mail address>
Sent: Friday, March 01, 2002 11:35 PM
Subject: [aspngregexp] Re: Changing case

[Original message clipped]
Reply to this message...
 
 
System.Text.RegularExpressions.MatchEvaluator
System.Text.RegularExpressions.Regex
System.Text.RegularExpressions.RegexOptions
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