PHP extracts the phone number in the string and verifies whether it is 11 digits

Suppose there is a mobile number 13632869999  Mixed in a pile of strings , You can use the following methods to get the phone number .

        $phone = ' Ha ha ha ha ha ha aaaaaaaa13632869999aaaabbbbbbbbbbbccccccccc Happy happy ';

        if (!is_numeric($phone)) {  // If it is a non pure digital mobile number    Start filtering 

           if(preg_match('/\d+/',$phone,$arr)){  // Filter to get pure numbers 

             $phone =  $arr[0];

             if(!preg_match("/^1[34578]{1}\d{9}$/",$phone)){  // Judge whether the pure number is normal 11 Cell phone number 
                 return ' Not 11 Cell phone number ！';

             }else{

                 return $phone;

             }

           }

        }