将字符串分成两部分
将一个字符串，按照开头的www 和A：将字符串分成两个字符串
$str = "www.asdfsfd.com,A:xiaohua,www.baidu.com,A:huanghuang,www.360buy.com,www.huahua.com,www.huanghuang.com,A:asdds,www.dd.com";将这个字符串分成两个字符串 输出为$a="www.asdfsfd.com,www.baidu.com,www.360buy.com,www.huahua.com,www.huanghuang.com,www.dd.com";
$b ="A:xiaohua,A:huanghuang,A:asdds";
------解决方案--------------------
preg_match_all("/www\.[a-z]*\.[a-z]*/is", $str, $out);
preg_match_all("/A:[a-z]*/is", $str, $out2);
------解决方案--------------------
$str_arr = explode(',',$str);
foreach($str_arr as $key=>$val){
  if(substr($val,0,3) == 'www'){
    $a_str .= $val.',';
  }else{
    $b_str .= $val.',';
  }
}
$a = substr($a_str,0,-1);
$b = substr($b_str,0,-1);
------解决方案--------------------

$str = "www.asdfsfd.com,A:xiaohua,www.baidu.com,A:huanghuang,www.360buy.com,www.huahua.com,www.huanghuang.com,A:asdds,www.dd.com";

preg_match_all("/(?:(www\..*?),
------解决方案--------------------
(A\:.*?)(?=,
------解决方案--------------------
$))/",$str,$match);

$str1 = preg_replace("/,{2,}/",",",implode(",",$match[1]));

echo preg_replace("/^,/","",$str1); 

echo "<br>";

$str2 =preg_replace("/(,{2,})/",",",implode(",",$match[2])); 

echo preg_replace("/^,/","",$str2);

------解决方案--------------------

$str = "www.asdfsfd.com,A:xiaohua,www.baidu.com,A:huanghuang,www.360buy.com,www.huahua.com,www.huanghuang.com,A:asdds,www.dd.com";

preg_match_all('/(www[\w.]+),?(A:\w+)?/',$str,$m);

echo join(',',$m[1]);

echo '<br>';

echo join(',',array_diff($m[2],array('')));

------解决方案--------------------

$str = "www.asdfsfd.com,A:xiaohua,www.baidu.com,A:huanghuang,www.360buy.com,www.huahua.com,www.huanghuang.com,A:asdds,www.dd.com";



preg_match_all('/(www[^,]+)
------解决方案--------------------
(A:[^,]+)/', $str, $res);

$a = join(',', array_diff($res[1], array('')));

$b = join(',', array_diff($res[2], array('')));