preg_match在我的情况下无法正常工作

Question

This is my code to get content between html tags.

$stringtext=file_get_contents($url);

$frm1=htmlspecialchars($_REQUEST['from1']);
$to1=htmlspecialchars($_REQUEST['to1']);

$dt= find_between($newstr,$frm1,$to1);

function find_between($string, $start, $end, $trim = true, $greedy = false)        {

$pattern = '/'.preg_quote($start,'\"').'(.*';
if (!$greedy) $pattern .= '?';
 $pattern .= ')'.preg_quote($end,'/').'/s';

preg_match($pattern, $string, $matches);
$string = $matches[0];
if ($trim) {
    $string = substr($string, strlen($start));
    $string = substr($string, 0,-strlen($end));
}

return $string;
}

It return null.

if I write pattern like this

$pattern = '/<td valign\="top">(.*?)<\/td>/s';

It works fine.

This is html form to enter value of frm1 and to1.

<form action="" method="post" id="frm1" style="display:none">


<table>
    <tr>
        <td>From: <input type="text" name="from1" /></td>
        <td>To: <input type="text" name="to1" /></td>
    </tr>
</table></form>

Answer 1

As Casimimir has already pointed out, use a Parser (eg SimpleXML ) instead.
Consider the following code with two alternatives:

<?php
$html = '
<form action="" method="post" id="frm1" style="display:none">

<table>
    <tr>
        <td>From: <input type="text" name="from1" /></td>
        <td>To: <input type="text" name="to1" /></td>
    </tr>
</table></form>
';

$xml = simplexml_load_string($html);

# traverse the DOM directly
$input_version1 = $xml->table->tr->td->input;

# use an xpath query to get the same element
$input_version2 = $xml->xpath("//form//input[@name='from1']")[0];

print_r($input_version1);
print_r($input_version2);
?>

A good introduction to SimpleXML can be found here .

Answer 2

function find_between($string, $start, $end, $trim = true, $greedy = false)        {
$start=htmlspecialchars_decode($start);
$end=htmlspecialchars_decode($end);

$pattern = '/'.preg_quote($start,'\"').'(.*';
if (!$greedy) $pattern .= '?';
 $pattern .= ')'.preg_quote($end,'/').'/s';

preg_match($pattern, $string, $matches);
$string = $matches[0];
if ($trim) {
$string = substr($string, strlen($start));
$string = substr($string, 0,-strlen($end));
}

return $string;
}