regular expression help

jaddy

Hi !

I want to get the keywords from the following Meta tag:

so I can get the string: smile,peace,hope

Any suggestions...

thx...

rIkLuNd

<?php

// I haven't tested this code!

$html = "<META NAME=\"keywords\" content=\"smile,peace,hope\">";

if(preg_match('#<META NAME="keywords" content="(.*?)">#',$html,$match)) {
$str = $match[0][1];
}

echo $str;

?>

jaddy

Thank you,

I've executed the script and the only result is the character 'M'.

BTW, consider that the meta tag could be:
<META NAME="keywords" content="smile,peace,hope">
or
<META content="smile,peace,hope" NAME="keywords" >
or
<META NAME=keywords content=smile,peace,hope> // no (")
or
<meta name="keywords" content="smile,peace,hope"> // lower case

thx...

rIkLuNd

<?php

// Your meta tag should look like this so that it's xhtml correct
// <meta name="keywords" content="smile,peace,hope" />

$html = "<meta name=\"keywords\" content=\"smile,peace,hope\" />";

if(preg_match('#<meta name="keywords" content="(.*?)">#',$html,$match)) {
$str = $match[1];
}

echo $str;

?>

xblue

well, he said he didn't test it.

a simple call to print_r($match) would probably have revealed that $match does get populated, the only thing is that it is a one-dimensional array, so the syntax to access elements was wrong.

the other issues:

case sensivity:
i-modifier http://www.php.net/manual/en/pcre.pattern.modifiers.php

missing quotes:
might be easiest to treat the different cases separately in an alternation, like

content=("[^"]+"|\\'[^\\']+\\'|\\S+)

the drawback: the quotes are parts of the match of this subpattern, but you can easily get rid of the with trim() or str_replace() when you output or process the match.

order of attributes:
depends on how precise you want the match to be. can you rely on each meta tag having a name attribute? then it might be enough to mark the name thing="keyword" part as optional and put it before and after the content part (watch the spaces).

jaddy

Thank xblue,

I have spent more than 6 hours working on it, but unfortunately I couldn't find the exact regular expression.

I've tried so much expressions and now I'am having a headace 😕 .

Could any body (with more experience in regular expressions) help me by building such pattern for me, and I'll be appreciated.

Thax.

jaddy

I have created many expressions including the following:

"<meta.+name.=.keywords.+content.=.>"

but the above one return a string from the <meta to the last of the file (which is </html>)

Also I have made something complicated just like:

"<meta.+name.=.(\"|[^{\"])keywords(\"|[^{\"]).+content.=.(\"|[^{\"]).(\"|[^{\"])[^>]}>"}}}

and

"<meta.+name.=.\"?keywords\"?.+content.=.\"?.\"?[^>]>"

but nothing worked

Any clue ???

xblue

keep in mind that quantifiers are greedy, consuming as much as possible unless marked as ungreegy by inserting a questionmark (or using the U-modifier).

also, this B[/B] doesn't make much sense, meaning "either a doublequote or any character that is not a doublequote".

jaddy

Thx...

Let me ask a question:

Suppose that I am having the following string:

 Peace

and I want to take out only the complete font tag which is:


How can I do this without continue parsing until the end of the line or the page.
What is the regular expression that let me stop when I find the first '>' after the font tag name.

Thanks

xblue

well, you want to match everything that is not a closing angular bracket, followed by the closing brackets, though using a negated character class seems pretty straightforward (modify according to your needs):

<font[^>]*>

jaddy

It works at last

Thanks xblue for help 🙂