Parse error: parse error, expecting PHP For Loop

.

function is_valid_isbn($isbn)
{
  $isbn_length  =  strlen($isbn);
  $isbn_sum     = 0;
  echo "this is the length :";
  echo $isbn_length;
  for($i=0; $i < $isbn_length; $i++) { $total += (substr($isbn, $i, 1) * (11-($i+1))); }
 return true;
 }

When i run this function i am getting following error can some one help me where is the err ??

Here is the error message

Parse error: parse error, expecting `';'' in C:\xa开发者_JAVA技巧mpp\htdocs\gbload\application\libraries\Isbnconv.php on line 47

Next time, pls tell us where is the line 47. See the fixed code below:

function is_valid_isbn($isbn)
{


  $isbn_length  =  strlen($isbn); //no br here
  $isbn_sum     = 0;//no br here
  echo "this is the length :"; //same 
  echo $isbn_length;//same
  for($i=0; $i < $isbn_length; $i++) //wrong here, missing the operator <
  { 
          $total += substr($isbn, $i, 1) * (11-$i+1); //too many ( )
  }//no br here
  return true;
}

for($i=0; $i$isbn_length; $i++) 

maybe it should be: for($i=0; $i==$isbn_length; $i++) or something like that...