Store Get-Values from form in Array PHP

I believe the following should work for you... This will take all the $_GETs that you supply and put them in a new array so you can modify them without affecting the original $_GET array.

if(is_array($_GET)){
 $newArr = $_GET; // modify $newArr['postFieldName'] instead of $_GET['postFieldName'] to preserve original $_GET but have new array. 
}

That solution there will dupe the $_GET array. $_GET is just an internal PHP array of data, as is $_POST. You could also loop through the GETs if you do not need ALL of the GETs in your new array... You would do this by setting up an accepted array of GETs so you only pull the ones you need (this should be done anyways, as randomly accepting GETs from a form can lead to some trouble if you are also using the GETs for database/sql functions or anything permission based).

if(is_array($_GET) && count($_GET) > 0){
     $array = array(); 
     $theseOnly = array("postName", "postName2"); 
     foreach($_GET as $key => $value){
      if(!isset($array[$key]) && in_array($key, $theseOnly)){ // only add to new array if they are in our $theseOnly array. 
       $array[$key] = $value; 
      } 
     }
     print_r($array); 
    } else {
     echo "No $_GET found."; 
    }

I would just add to what @Nerdi.org said.

Specifically the second part, instead of looping through the array you can use either array_intersect_key or array_diff_key

$theseOnly = array("postName", "postName2");
$get = array_intersect_key( $_GET, array_flip($theseOnly);

//Or

 $get = array_diff_key( $_GET, array_flip($theseOnly);

array_intersect_key

array_intersect_key() returns an array containing all the entries of array1 which have keys that are present in all the arguments.

So this one returns only elements you put in $theseOnly

array_diff_key

Compares the keys from array1 against the keys from array2 and returns the difference. This function is like array_diff() except the comparison is done on the keys instead of the values.

So this one returns the opposite or only elements you don't put in $theseOnly

And

array_flip

array_flip() returns an array in flip order, i.e. keys from array become values and values from array become keys.

This just takes the array of names with no keys (it has numeric keys by default), and swaps the key and the value, so

 $theseOnly = array_flip(array("postName", "postName2"));
 //becomes
 $theseOnly = array("postName"=>0, "postName2"=>1);

We need the keys this way so they match what's in the $_GET array. We could always write the array that way, but if your lazy like me then you can just flip it.

session_start();
if(!isset($_SESSION['TestArray'])) $_SESSION['TestArray'] = array();
if(is_array($_GET)){
    $_SESSION['TestArray'][] = $_GET;
}
print_r($_SESSION['TestArray']);

Thanks everybody for helping! This worked for me!