if / elseif / else问题[关闭]

Question

I am creating a whitelist if you will for a user to input data. I am getting stuck on the elseif statements.

This is my code :

public function is_valid_data($data)
   {

     if(strlen($data > 9))
     {
       $this -> set_message('is_valid_data', 'Field needs to be less than 9 characters');
       return FALSE;
     }
     elseif(strlen($data < 9))
     {
       $this -> set_message('is_valid_data', 'Field can not be under 9 characters');
       return FALSE;
     }
     elseif((substr($str, 0, 1) !== 'testing') || (substr($str, 0, 1) !== 'test'))
     {
       $this -> set_message('is_valid_data', 'Please re-submit data!');
       return FALSE;
     }
     elseif(!preg_match("/^[0-9]/", $str))
     {
       $this -> set_message('is_valid_data', 'Please dont forget about the numbers!');
       return FALSE;
     }
     else
     {
       return TRUE;
     }

   }

For some reason even if $data is 9 characters the first if statements goes through, then the second one fails and I keep getting 'Field can not be under 9 characters' even though the $data is exactly 9 characters. I am returning false because in another script I have the function call is_valid_data($data) and if this function returns a false then it will return the error to the user. If it returns true then the data is valid and we can continue

I can't seem to shake this issue.

Answer 1

if(strlen($data) > 9)

instead of

if(strlen($data > 9))