您必须使用正则表达式匹配字符串(希望您使用PCRE ...).

You'll have to match the string using a regular expression (I hope you have PCRE...).

$el=$html->find('meta[http-equiv=Content-Type]',0)
$fullvalue = $el->content;
preg_match('/charset=(.+)/', $fullvalue, $matches);
echo $matches[1];

不是很健壮，但应该可以.

Not very robust, but should work.