Programming Forums > Web Development and Design > PHP

Sane · Jan 2nd, 2008, 11:48 AM

I have a string handled by PHP. What's the best way to strip all "font" tags from that string? For example, I want $new_mystr to be obtained from $mystr.

E.G. Input

(Toggle Plain Text)

$mystr = '<div class="content"><p>Hello to all. <font face="Calibri"><font size="3">Goodbye</font></font></p></div>';

E.G. Output

(Toggle Plain Text)

$new_mystr = '<div class="content"><p>Hello to all. Goodbye</p></div>';

mark · Jan 2nd, 2008, 1:04 PM

what about strip_tags function

http://us.php.net/manual/en/function.strip-tags.php

Sane · Jan 2nd, 2008, 1:12 PM

Great!

Thank-you.

But I can only use this temporarily, because it's not exactly what I need. I want to specify tags for inclusion. Not for exclusion.

So currently I can go:

(Toggle Plain Text)

strip_tags($text, '<p><div>');

However, that's specifying tags to exclude. Whereas I want something like this:

(Toggle Plain Text)

strip_tags_only($text, '<font>');

To specify the only tags included in the stripping.

null_ptr0 · Jan 2nd, 2008, 5:04 PM

Remove Post Please

Sane · Jan 2nd, 2008, 5:06 PM

Quote:

Originally Posted by null_ptr0

str_replace(string, string)

No. Sorry. Good try? But no.

null_ptr0 · Jan 2nd, 2008, 5:09 PM

ereg_replace
preg_replace
RegEx - use them.

Sane · Jan 2nd, 2008, 5:34 PM

Yes, so I can do something like:

 php Syntax (Toggle Plain Text) 
function strip_tag($text, $tag) {
    return ereg_replace('</?'.$tag.'[^>]*>', '', $text);
}
 
echo strip_tag($text, 'font');
function strip_tag($text, $tag) {
    return ereg_replace('</?'.$tag.'[^>]*>', '', $text);
}

echo strip_tag($text, 'font');

I'd still like to see if there's something tried and tested though.

null_ptr0 · Jan 2nd, 2008, 5:36 PM

Regex aren't tested?

Sane · Jan 2nd, 2008, 5:47 PM

You misunderstand me.

There are always exceptions that standard library functions are built to handle. This simple regex statement is breakable.

For instance, if you gave my code:

(Toggle Plain Text)

echo strip_tag('<font>Blah', 'font');

It would output:

(Toggle Plain Text)

Blah

When I would prefer it to output:

(Toggle Plain Text)

<font>Blah

So the user can see that the original HTML was malformed.

Another example is if the tag is incomplete.

(Toggle Plain Text)

echo strip_tag('<font face="arial". Hello World!</font> This is some more text.', 'font');

You will get:

(Toggle Plain Text)

This is some more text.

Which is again, not satisfactory.

That's why it's best to leave it to a function which handles input with regard to the existing standards. Anyways, this shouldn't even need explanation.

At this point, from the lack of other replies, I'd say nothing else exists. I'll stick with my regex, which does work fine.

grimpirate · Jan 2nd, 2008, 8:59 PM

I would suggest taking a look at some BBCode snippets as that is the most popular method apparently of stripping tags and creating your own "tags". It's what most of the forums use. My own forum has a function I created called parsePost (located in the _udf folder under parsePost.php). You can take a look at it as it only allows certain tags to be used and then parses out the remainder. However, the function is rather long and bloated, it needs to be refined and it also doesn't check for flaws where the tags haven't been closed. As I recall it explodes about the < character and then analyzes the initial portion of each line to determine if it is indeed an HTML tag or just a less than or some other tag I've no interested in allowing to be rendered.

Jan 2nd, 2008, 11:48 AM	#1
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	Best Way To Strip Certain Tags From A String I have a string handled by PHP. What's the best way to strip all "font" tags from that string? For example, I want `$new_mystr` to be obtained from `$mystr`. E.G. Input (Toggle Plain Text) $mystr = '<div class="content"><p>Hello to all. <font face="Calibri"><font size="3">Goodbye</font></font></p></div>'; $mystr = '<div class="content"><p>Hello to all. <font face="Calibri"><font size="3">Goodbye</font></font></p></div>'; E.G. Output (Toggle Plain Text) $new_mystr = '<div class="content"><p>Hello to all. Goodbye</p></div>'; $new_mystr = '<div class="content"><p>Hello to all. Goodbye</p></div>';

Jan 2nd, 2008, 1:04 PM	#2
mark Newbie Join Date: Mar 2006 Posts: 19 Rep Power: 0	Re: Best Way To Strip Certain Tags From A String what about strip_tags function http://us.php.net/manual/en/function.strip-tags.php

Jan 2nd, 2008, 1:12 PM	#3
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	Re: Best Way To Strip Certain Tags From A String Great! Thank-you. But I can only use this temporarily, because it's not exactly what I need. I want to specify tags for inclusion. Not for exclusion. So currently I can go: (Toggle Plain Text) strip_tags($text, '<p><div>'); strip_tags($text, '<p><div>'); However, that's specifying tags to exclude. Whereas I want something like this: (Toggle Plain Text) strip_tags_only($text, '<font>'); strip_tags_only($text, '<font>'); To specify the only tags included in the stripping.

Jan 2nd, 2008, 5:04 PM	#4
null_ptr0 12 years old Join Date: Nov 2007 Posts: 105 Rep Power: 0	Remove Post Please Remove Post Please Last edited by null_ptr0; Jan 2nd, 2008 at 5:06 PM. Reason: REMOVE POST PLEASE

Jan 2nd, 2008, 5:09 PM	#6
null_ptr0 12 years old Join Date: Nov 2007 Posts: 105 Rep Power: 0	Re: Best Way To Strip Certain Tags From A String ereg_replace preg_replace RegEx - use them.

Jan 2nd, 2008, 5:34 PM	#7
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	Re: Best Way To Strip Certain Tags From A String Yes, so I can do something like: php Syntax (Toggle Plain Text) function strip_tag($text, $tag) { return ereg_replace('</?'.$tag.'[^>]>', '', $text); } echo strip_tag($text, 'font'); function strip_tag($text, $tag) { return ereg_replace('</?'.$tag.'[^>]>', '', $text); } echo strip_tag($text, 'font'); I'd still like to see if there's something tried and tested though.

Jan 2nd, 2008, 5:36 PM	#8
null_ptr0 12 years old Join Date: Nov 2007 Posts: 105 Rep Power: 0	Re: Best Way To Strip Certain Tags From A String Regex aren't tested?

Jan 2nd, 2008, 5:47 PM	#9
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 2,069 Rep Power: 6	Re: Best Way To Strip Certain Tags From A String You misunderstand me. There are always exceptions that standard library functions are built to handle. This simple regex statement is breakable. For instance, if you gave my code: (Toggle Plain Text) echo strip_tag('<font>Blah', 'font'); echo strip_tag('<font>Blah', 'font'); It would output: (Toggle Plain Text) Blah Blah When I would prefer it to output: (Toggle Plain Text) <font>Blah <font>Blah So the user can see that the original HTML was malformed. Another example is if the tag is incomplete. (Toggle Plain Text) echo strip_tag('<font face="arial". Hello World!</font> This is some more text.', 'font'); echo strip_tag('<font face="arial". Hello World!</font> This is some more text.', 'font'); You will get: (Toggle Plain Text) This is some more text. This is some more text. Which is again, not satisfactory. That's why it's best to leave it to a function which handles input with regard to the existing standards. Anyways, this shouldn't even need explanation. At this point, from the lack of other replies, I'd say nothing else exists. I'll stick with my regex, which does work fine. Last edited by Sane; Jan 2nd, 2008 at 5:58 PM.

Jan 2nd, 2008, 8:59 PM	#10
grimpirate King of Portal Join Date: Sep 2005 Posts: 439 Rep Power: 4	Re: Best Way To Strip Certain Tags From A String I would suggest taking a look at some BBCode snippets as that is the most popular method apparently of stripping tags and creating your own "tags". It's what most of the forums use. My own forum has a function I created called parsePost (located in the _udf folder under parsePost.php). You can take a look at it as it only allows certain tags to be used and then parses out the remainder. However, the function is rather long and bloated, it needs to be refined and it also doesn't check for flaws where the tags haven't been closed. As I recall it explodes about the < character and then analyzes the initial portion of each line to determine if it is indeed an HTML tag or just a less than or some other tag I've no interested in allowing to be rendered. __________________ Lo, there do I see my father. 'Lo, there do I see My mother, and my sisters, and my brothers. 'Lo, there do I see The line of my people... Back to the beginning. 'Lo, they do call to me. They bid me take my place among them. In the halls of Valhalla... Where the brave... May live... ...forever.. GrimBB \| Mimesis

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Programming Forums > Web Development and Design > PHP

Best Way To Strip Certain Tags From A String