php - The second argument to copy() function cannot be a directory and move_uploaded_file(): Unable to move

in the code

if(isset($_POST['submit'])){


 $post_image=$_FILES['post_image']['name'];
 $post_image_tmp=$_FILES['post_image']['tmp_name'];

    if($post_image='' ){

        echo "";
        exit();

    }
else{

move_uploaded_file($post_image_tmp,"news_images/$post_image");
?>

I get this error

Warning: move_uploaded_file(): The second argument to copy() function
cannot be a directory in C:\xampp\htdocs\MyCMS\admin\insert_post.php
on line 107

Warning: move_uploaded_file(): Unable to move
'C:\xampp\tmp\php946C.tmp' to 'news_images/' in
C:\xampp\htdocs\MyCMS\admin\insert_post.php on line 107

Please help I'am just newbie.

Answer

= is assignment operator.
use comparison operator == here.

if($post_image == '' ) {