2014-10-10 13:00
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PHP DOMXPath使用双引号失败,带单引号

I wrote a little script that extracts information from a web site using PHP's DOMXPath class.
I query for <div class="sku" /> and execute a substring-before on the result. The result contains text, non breaking spaces, a line break and more text.
So what I'm trying to do is cut before the &nbsp;&nbsp; . It works fine when I use the following query:

$query = "substring-before(//div[@class='sku'],'\xC2\xA0\xC2\xA0

but fails as soon as I change the quotes (which shouldn't make any difference):

$query = 'substring-before(//div[@class="sku"],"\xC2\xA0\xC2\xA0


$query = 'substring-before(//div[@class=\'sku\'],\'\xC2\xA0\xC2\xA0

How is this possible and how can I overcome this?

Live example here: http://codepad.viper-7.com/R1rCaj

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2条回答 默认 最新

  • dongye1934
    dongye1934 2014-10-10 15:03

    The style of quotes makes a difference because when a string is enclosed in double-quotes PHP will interpret more escape sequences for special characters - including what you're using for non-breaking space \xC2\xA0, carriage return , and newline .

    When you have these enclosed in single-quotes '\xC2\xA0 ', like in your second two queries, PHP treats them as those literal characters - backslash, x, C, 2... etc.

    A little extra syntax highlighting may help show this off, escape sequences in orange:

    enter image description here

    If your string already has what would be escape sequences in it as literal characters, and there's no way to get that corrected*, you're in the kinda dirty position of replacing them yourself.

    This preg_replace_callback() will take care of the sort of sequences in your example, and it's trivial to extend to the rest of the escape sequences supported by double-quotes:

    // Known good.
    $query1 = "substring-before(//div[@class='sku'],'\xC2\xA0\xC2\xA0
    // Known bad.
    $query2 = 'substring-before(//div[@class=\'sku\'],\'\xC2\xA0\xC2\xA0
    $query2 = preg_replace_callback(
        function ($matches) {
            switch (substr($matches[0], 0, 2)) {
                case '':
                    return "";
                case '
                    return "
                case '\x':
                    return hex2bin(substr($matches[0], 2));
    var_dump($query1 === $query2); // Now equal?



    (*Really, you should get this fixed at the source.)

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  • dongliping003116
    dongliping003116 2014-10-10 13:26

    you can do this easy with simple_html_dom for download : http://sourceforge.net/projects/simplehtmldom/files/ Manual : http://simplehtmldom.sourceforge.net/manual.htm

        // include simple html dom library
        // get html in $html var
        // find your class div.sku (plaintext) or you can get (innertext)
    echo $results ;
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