PHP - Replacing Broken Images.

I copied the code for password_hash at php.net:

	<?php
/**
 * In this case, we want to increase the default cost for BCRYPT to 12.
 * Note that we also switched to BCRYPT, which will always be 60 characters.
 */
$options = [
    'cost' => 12,
];
echo password_hash("rasmuslerdorf", PASSWORD_BCRYPT, $options);
?>
	

and changed it for use in my login page:

	$options = ['cost' => 12,];
    $user = mysqli_real_escape_string($db_link,$_GET['username']);
    $pass = password_hash($_GET['password'], PASSWORD_BCRYPT, $options);
	

but my page keeps saying invalid user/pass. Upon echoing the $pass I find that the result changes EACH time. so I created a test page that runs the code from php.net (verbatim code) 20x and I got:

[pre]

 $2y$10$Nlf0J520viR4C5jd3nIdd.6M3OMKACx503Jm3PiXDYZIs.13XAheq
$2y$10$SO1ip3JI.EGjUJb3JYUDSeAUszg6A3UBX9b.ENk2aythAuxQ1apxS
$2y$10$Ub7cQSbFWXhkLrzm3ldGGe8FfgsOjS99vgj9l801yqXgPjvJmVpsm
$2y$10$8fNzz/tmrg8tLdHOk0r7GOh0j1frKN3ujA/qzrFHi/s22jMO/hbri
$2y$10$o.5LnDxkhw/YNxJT16fuIOiQbnhHKs51SqFTqQ3KsflY6nYV.HLLm
$2y$10$zQZiauRe6tuF2rGd1XGcO.E7ekhfP68Sqih8ll9Om7n5c2NO3tPSu
$2y$10$uLZXDAQu14EW8P4CMMICBuvRv0wOEAxghzJV1c9UuNK7yTRJNNdjO
$2y$10$P6Uy4/PDOnE9zv/VxRAWFebKY/qYXj1unIrTvV42xUxe.zXx3ut2W
$2y$10$uHb8qdh3CGe0BkXdyuThHu0vgAH5bxEPYMe0VK410Q7xqcAlC.xuy
$2y$10$xXwbec0Cn0JcMorGgmmRY.qHW.N1pNoYq.2V.IAQHsCDYPXtgQyJ6
$2y$10$w88m.M6BmVVoYYBhM1IAquOIb4NH9n093nQmdzhKm0Fq2ykgcZFZm
$2y$10$IkVTs7.z4rZt5/rkgRQnKeXfINb7VTqXxTDRZB9caR4X0rwKtdhIW
$2y$10$XyjX0X0I.l4Ct9eF4zhhz.S5Cg/Ppqf3veL9ciehjBr/2Rp8usPCm
$2y$10$iJkhIWl95TVlA4hw2nltd./YmyXA2.abqTu8WFs/YuEvJsndosv6W
$2y$10$kwVNtAaKxG8z2m.D0evl..Xx64NWPxbFAIBjCDLBfgiJncgniBB7S
$2y$10$m8ZyiI7HhXutyTZGySit/O3lmAGsIlfRqEcYc7eCV2XS9TS1Sw9/y
$2y$10$uYDilXy1HKT9M6DiPUhAe.3W5teCpkTF4x5UgVYiJctz4HXNMzU9e
$2y$10$0HDD2quyh2AfMeF41PbKTu7PGTPn2fcl42HLxweaIHay9KbPDrEh6
$2y$10$qc0Kt5VtkrslpLlQmvq5a.dboTbf8qEif9KOwYwjoGGh6Q.xoN8JK

[/pre]

Is password_hash broken? or am I mistaken to think that it's supposed to return the same output everytime fror the same input?

<?php
  //CORS header
  header("Access-Control-Allow-Origin: *");


  //Capture parameter
  
  $create = $_POST['create'];
  $fuser = $_POST['fuser'];




 if (!file_exists("uploads/$fuser/$create"));
 {
 if ($f = fopen("uploads/$fuser/$create", 'w')) {
    fwrite($f, 1);
    fclose($f);
    echo 'OK';
     }


  }     
  else
{
  $f = fopen("uploads/$fuser/$create", 'w')
   fwrite($f, 5);
    fclose($f);
    echo 'FAIL' ;
}


 
?>

<?php
  //CORS header
  header("Access-Control-Allow-Origin: *");


  //Capture parameter
  
  $create = $_POST['create'];
  $fuser = $_POST['fuser'];




 if (!file_exists("uploads/$fuser/$create"));
 {
 if ($f = fopen("uploads/$fuser/$create", 'w')) {
    fwrite($f, 1);
    fclose($f);
    echo 'OK';
     }


  }

If I have a web page located he

www . company . com / how-to-repair-your-computer.html

And I decide to re-structure my website like this

www . company . com / articles / how-to-repair-your-computer.html

How do I make sure that people don't search and end up at the old, now broken, link?

It seem inevitable that as a website grows, that you will want to re-organize things.  What is the best way to make sure that anyone who searches or clicks on an old link - say from an email from a friend - doesn't get a 404 error?

Also, how do you avoid ruining a web pages rank on Google after you move things?  (I think if the URL changes, Google makes you start all over as far as getting listed on page-1 and all of that?

Is this something I have to hande on my end, or is it a Google issue, or something else?