Looking for duplicate in local text file

Question

please could someone help me with this duplicate checking function. I'm still quite fresh when it comes to PHP, so please excuse me, if this is a simple fix.

I'm storing a list of email addresses to a file called list.txt. Here is the content of the file (each on a new line):

[email protected]
[email protected]
[email protected]

Now I have a function (not working) that should check if email is already in the list:

function is_unique($email) {
   $list = file('list.txt');

   foreach($list as $item){
      if($email == $item){
          return false;
          die(); 
      }
   }
   return true;
}

When I call the function in this test, with an existing email address, it still returns true:

if( is_unique('[email protected]') ) {
    echo "Email is unique";
} else {
    echo "Duplicate email";
}

// Returns true even though [email protected] is in the list

I appreciate anyone's input.

Answer 1

It is fine to use list but you must trim() the item when iterating through the list as they still have the linebreak:

if($email == trim($item))

Update: As Nick mentioned, the optional flag of FILE_IGNORE_NEW_LINES would dramatically cut down on execution speed and code:

function is_unique($email) {
   $list = file('list.txt',FILE_IGNORE_NEW_LINES);
   return in_array($email,$list) ? false : true;  
}

Answer 2

Either remember to trim your email, or a better solution would be to use FILE_IGNORE_NEW_LINES while you use the file function, which would allow you to use PHP's inbuilt array searching (should be faster). For example:

function is_unique($email) {
   $list = file('list.txt',FILE_IGNORE_NEW_LINES);

   return !in_array($email,$list);
}