Extracting the body text of an HTML document using PHP
I know it's better to use DOM for this purpose but let's try to extract the text in this way:
<?php
$html=<<<EOD
<html>
<head>
</head>
<body>
<p>Some text</p>
</body>
</html>
EOD;
preg_match('/<body.*?>/', $html, $matches, PREG_OFFSET_CAPTURE);
if (empty($matches))
exit;
$matched_body_start_tag = $matches[0][0];
$index_of_body_start_tag = $matches[0][1];
$index_of_body_end_tag = strpos($html, '</body>');
$body = substr(
$html,
$index_of_body_start_tag + strlen($matched_body_start_tag),
$index_of_body_end_tag - $index_of_body_start_tag + strlen($matched_body_start_tag)
);
echo $body;
The result can be seen here: http://ideone.com/vH2FZ
As you can see, I am getting more text than expected.
There is something I don't understand, to get the correc开发者_开发知识库t length for the substr($string, $start, $length) function, I am using:
$index_of_body_end_tag - $index_of_body_start_tag + strlen($matched_body_start_tag)
I don't see anything wrong with this formula.
Could somebody kindly suggest where the problem is?
Many thanks to you all.
EDIT:
Thank you very very much to all of you. There is just a bug in my brain. After reading your answers, I now understand what the problem is, it should either be:
$index_of_body_end_tag - ($index_of_body_start_tag + strlen($matched_body_start_tag));
Or:
$index_of_body_end_tag - $index_of_body_start_tag - strlen($matched_body_start_tag);
The problem is that your string have new lines where . in the pattern only matches single lines, you need to add /s modifier to make . to match multi-lines
Here is my solution, I prefer it this way.
<?php
$html=<<<EOD
<html>
<head>
</head>
<body buu="grger" ga="Gag">
<p>Some text</p>
</body>
</html>
EOD;
// get anything between <body> and </body> where <body can="have_as many" attributes="as required">
if (preg_match('/(?:<body[^>]*>)(.*)<\/body>/isU', $html, $matches)) {
$body = $matches[1];
}
// outputing all matches for debugging purposes
var_dump($matches);
?>
Edit: I am updating my answer to provide you with better explanation why your code fails.
You have this string:
<html>
<head>
</head>
<body>
<p>Some text</p>
</body>
</html>
Everything seems to be fine with it but actually you have non-print characters (new line characters) on each line. You have 53 printable characters and 7 non printable (new lines, \n == 2 characters actually for each new line).
When you reach this part of the code:
$index_of_body_end_tag = strpos($html, '</body>');
You get the correct position of </body> (starting at position 51) but this counts the new lines.
So when you reach this line of code:
$index_of_body_start_tag + strlen($matched_body_start_tag)
It it evaluated to 31 (new lines included), and:
$index_of_body_end_tag - $index_of_body_start_tag + strlen($matched_body_start_tag)
It is evaluated to 51 - 25 + 6 = 32 (characters you have to read) but you only have 16 printable characters of text between <body> and </body> and 4 non printable characters (new line after <body> and new line before </body>). And here is the problem, you have to group the calculation (prioritize) like so:
$index_of_body_end_tag - ($index_of_body_start_tag + strlen($matched_body_start_tag))
evaluated to 51 - (25 + 6) = 51 - 31 = 20 (16 + 4).
:) Hope this helps you to understand why prioritizing is important. (Sorry for misleading you about newlines it is only valid in regex example I gave above).
Personally, I wouldn't use regex.
<?php
$html = <<<EOD
<html>
<head>
<title>Example</title>
</head>
<body>
<h1>foobar</h1>
</body>
</html>
EOD;
$s = strpos($html, '<body>') + strlen('<body>');
$f = '</body>';
echo trim(substr($html, $s, strpos($html, $f) - $s));
?>
returns <h1>foobar</h1>
The problem is in your substr computation of the ending index. You should substract all the way:
$index_of_body_end_tag - $index_of_body_start_tag - strlen($matched_body_start_tag)
But you are doing:
+ strlen($matched_body_start_tag)
That said, it seems a little overkill considering you can do it using preg_match only. You just need to make sure you match across new lines, using the s modifier:
preg_match('/<body[^>]*>(.*?)<\/body>/s', $html, $matches);
echo $matches[1];
Outputs:
<p>Some text</p>
Somebodys probably already found your error, i didn't read all the replys.
The algebra is wrong.
code is here
Btw, first time seeing ideone.com, thats pretty cool.
$body = substr(
$html,
$index_of_body_start_tag + strlen($matched_body_start_tag),
$index_of_body_end_tag - ($index_of_body_start_tag + strlen($matched_body_start_tag))
);
or ..
$body = substr(
$html,
$index_of_body_start_tag + strlen($matched_body_start_tag),
$index_of_body_end_tag - $index_of_body_start_tag - strlen($matched_body_start_tag)
);
加载中,请稍侯......
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