Question: Most solutions I found are for front-end use. This is for a plugin, so the all activity is in the back-end.

How do I get the page ID that's being currently use(edited) in the admin?

**Note** I'm out of the loop. I just need to get the ID of page(not posts) that I'm currently seeing in the back-end.

Answer: 
You can add this code in functions.php file and it will give you a meta box above the publish settings box when editing a post or page.

```
 <?php

function cf_post_id() {
    global $post;

   // Get the data
   $id = $post->ID;

   // Echo out the field
   echo '<input type="text" name="_id" value="' . $id . '" class="widefat" disabled />';
  }

 function ve_custom_meta_boxes() {
    add_meta_box('projects_refid', 'Post ID', 'cf_post_id', 'post', 'side', 'high');
    add_meta_box('projects_refid', 'Page ID', 'cf_post_id', 'page', 'side', 'high');
   }
   add_action('add_meta_boxes', 've_custom_meta_boxes');

?>

```
You just use this code in the **functions.php** file, It will give you a current edit page or post ID

```
function get_the_current_page_id(){
$post_id = null;
if( isset( $_REQUEST['post']) || isset($_REQUEST['post_ID'] ) ){
    $post_id = empty( $_REQUEST['post_ID'] ) ? $_REQUEST['post'] : $_REQUEST['post_ID' ];
}

//print_r($post_id) For check
//die();
}

//get_the_current_page_id() //Call the function

```