html主体和header中charset

# 如果body中没有charset ，则在header中提取
$meta = get_meta_charset($html);
$charset = preg_match("/charset=[^\w]?([-\w]+)/i", $meta, $temp) ? strtolower($temp[1]): "";

if(empty($charset)){
    $header = print_r($html_array['header'], true);
    $charset = preg_match("/charset=[^\w]?([-\w]+)/i", $header, $temp) ? strtolower($temp[1]): "";
}
echo $charset;
if($charset !== 'utf-8' and !empty($charset)){
    $html = mb_convert_encoding($html, 'utf-8', $charset);
}

function get_meta_charset($html){
    // $charset = preg_match("/<meta.+?charset=[^\w]?([-\w]+)/i", $html, $temp) ? strtolower($temp[1]):"";
    preg_match_all('/<meta.*?>/i', $html, $matches);
    $meta = '';
    foreach($matches[0] as $value){
        $value = strtolower(trim($value));
         # 多个空格转为一个空格
        $value = preg_replace("/\s(?=\s)/", "\\1", $value);
         // $value = preg_replace("/ {2,}/", "", $value); # {2,}前面的空格不能少
        $value = preg_replace("/'/", '"', $value);
        $value = str_replace(array(' "', '=" '), array('"', '="'), $value);
        $value = str_replace(array('= ', ' ='), array('=', '='), $value);
        if(strpos($value, 'charset') !== false) $meta .= $value . "\n";
    }
    return $meta;
}