uc-remarketing.php

<?php
/*
Plugin Name: UC Google Remarketing
Author: Dessalegne Chekol
Version: 1.0
Description: Adds Google AdWords Remarketing code on all pages
*/

add_action('wp_footer', 'google_script');



function google_script()
{ 
   
    $regex = '/^\d+$/';
	if ( preg_match($regex, get_option( 'my_google_id', '' ))&& (get_option( 'my_google_id', '' )!=null)) {
    
		 
		 $x=get_option( 'my_google_id', '' );
		  ?>
		  <script type="text/javascript">
				/* <![CDATA[ */
				var google_conversion_id = <?php echo $x;?>;
				var google_custom_params = window.google_tag_params;
				var google_remarketing_only = true;
				/* ]]> */
				</script>
				<script type="text/javascript" src="//www.googleadservices.com/pagead/conversion.js">
				</script>
				<noscript>
				<div style="display:inline;">
				<img height="1" width="1" style="border-style:none;" alt="" src="//googleads.g.doubleclick.net/pagead/viewthroughconversion/<?php echo $x;?>/?value=0&amp;guid=ON&amp;script=0"/>
				</div>
				</noscript>
<?php
	 }
	
}

function register_fields()
{
    register_setting('general', 'my_google_id', 'esc_attr');
    add_settings_field('my_google_id', '<label for="my_google_id">'.__('Google Remarketing ID' , 'my_google_id' ).'</label>' , 'print_custom_field', 'general');
}

function print_custom_field()
{
    
	$regex = '/^\d+$/';
	if ( preg_match($regex, get_option( 'my_google_id', '' )) ) {
					$value = get_option( 'my_google_id', '' );
					echo '<input type="text" id="my_google_id" name="my_google_id" value="' . esc_attr( $value ) . '" />';
					}   
	else
	 echo '<input type="text" id="my_google_id" name="my_google_id" value="" />';
		 
    
}

add_filter('admin_init', 'register_fields');