PHP 拆分文字，将一串文字拆分成一个一个的文字

/*
 * 处理封面标题 文字竖排
 * */
function get_pdf_title_cl($str){
    if($str){
        preg_match_all("/[0-9]{1}/",$str,$arrNum);/*检测数字数量*/
        preg_match_all("/[a-zA-Z]{1}/",$str,$arrAl);/*检测字母数量*/
        $newStr = preg_replace('/[^\x{4e00}-\x{9fa5}]/u', '', $str);/*检测文字数量*/
        $zifu =  mb_strlen($newStr,"utf-8");
        $shuzi_num = count($arrNum[0]);
        $zimu_num = count($arrAl[0]);
        $zifu_num = $zifu;
        $num = $shuzi_num+$zimu_num+$zifu_num;
        $arr = '';
        for ($i=0;$i<$num;$i++){
            $wenzi = mb_substr($str,$i,1,'utf-8');
            $arr = $arr.'<p>'.$wenzi.'</p>';
        }
        $data['title'] = $arr.'<p>销</p><p>售</p><p>合</p><p>同</p>';
        $data['status'] = 1;
        /*if($num <= 8){
        }else{
            $data['title'] = $str.'销售合同';
            $data['status'] = 2;
        }*/
        dump($data);die();
        return $data;
    }else{
        return '';
    }
}

效果：

array(2) {
  ["title"] => string(142) "<p>转</p><p>轮</p><p>+</p><p>三</p><p>床</p><p>R</p><p>T</p><p>O</p><p>废</p><p>气</p><p>处</p><p>销</p><p>售</p><p>合</p><p>同</p>"
  ["status"] => int(1)
}