php怎么截取逗号之前的字符

$str='aaaaa,bbbbbbb,ccccc';
if(strpos($str,',')){
	preg_match('/([^,]+?),/i',$str,$match);
}

print_r($match[1]);
/*
aaaaa
*/

$s = 'aaaaa,bbbbbbb,ccccc';
echo strtok($s, ',');

$string = '111a,111';
            $flag = strpos($string, ',');
            if($flag !== FALSE){
                $arr = explode(',', $string);
                echo $arr[0];
            }else{
                echo $string;
            }