我正在用PHP练习RegEx。 为什么这个简单的regExp不起作用？

Question

I am practicing RegEx in PHP. I know it is not that good to use it for HTML string manipulation but there are times when DOMDocument is not available in the PHP environment I work with.

$a ='bsrc="lalala"';

$t = preg_replace('/(src="([^"]*)")/i', '\2', $a);

So I am trying to get lalala from the string but for some reasons it doesn't work. I got blalalaa in return;

I tried escaping the " and write '/(src=\\"([^\\"]*)\\")/i' but to no avail. I am doing it in a preg_replace_callback function, can that be the reason?

Appreciate any help!

Answer 1

You should change your regular expression as

src=\"([^\"]*)\"

Debuggex Demo

Final PHP must be

$t = preg_replace('~src=\"([^\"]*)\"~i', '\2', $a);

Answer 2

If you are trying to get a match then you need to use preg_match instead of preg_replace :

$a ='<src="lalala"a';
if (preg_match('/<src="([^"]*)"/i', $a, $m))
    print_r($m[1]);

Answer 3

This is because you are searching for <src and the string does not have this. Your test string should be <src="lalala" and not bsrc..

Answer 4

Try this:

    $a ='bsrc="lalala"a';

    if (preg_match('/src="(.*)"/i', $a, $matches))
    {
            if (isset($matches[1]))
            {
                 echo "Found value: " .$matches[1]. "\n";
            }
            else 
            {
                echo "Not found\n";
            }
    }
    else
    {
        echo "Not found\n";
    }