PHP页面使用location：from url参数重定向

I have a redirect PHP page which checks a URL Parameter and redirects to one of two pages depending on if the variable 'shore' is either 1 or not. My problem however, is that no matter what I do, the page is redirecting to the first option. Can anyone see anything obvious that I am missing?

Many thanks

<?php

  require_once('Connections/ships.php');

if ($_GET['shore'] = "1") {
   header( 'Location: shore_establishment.php?ship_id=' .urlencode($_GET['ship_id']) . "?shore=1");
   //echo"first";
} else if ($_GET['shore'] = "0") {
    header( 'Location: shipinfo.php?ship_id=' .urlencode($_GET['ship_id']). "?shore=0");
   //echo"second";
};

?>

Like, @CommuSoft said, and your second ? in your $_GET request should be an & instead.

You should use == instead of = to check the content of a variable

Furthermore I would advise you to use else instead of else if since there are only two options (this is more robust and in case in the end a third variable is introduced, the page would still do something).