index.php

<?php
// return location from user ip
require 'IP.class.php';
$rip=$_SERVER["REMOTE_ADDR"];
$lar = Ip::find($rip);

$i = count($lar) - 1;
$loc = "地球";
while($i >=0 ){
	if(strlen($lar[$i]) > 0 ) {
		$loc = $lar[$i];
		break;
	}
	$i --;
}
echo $loc;

SomeMoreSentence.php

<?php
/**
 *Plugin Name: SomeMoreSentence
 *Version:     0.1
 *Plugin URI:  http://argcv.com
 *Description:  append some more sentence after the end of your post
 *Author:      Yu Jing
 *Author URI:  http://argcv.com/about
 */

function SomeMoreSentence($outer){
	if(!is_singular()){ return $outer; }
	global $post;
  
  $tmp = "<blockquote>来自<a id='remote_loc'></a>的你，很高兴你能看到这儿。若本文对你有所用处，或者内容有什么不足之处，敬请毫不犹豫给个回复。谢谢！</blockquote><script type='text/javascript'>
$(document).ready(function(){
	$.get('/api/ip/', function(data,status){ 
		$('#remote_loc').text(data);
	});
});</script>";
        $outer = $outer.$tmp;        
	return $outer;
}

 add_filter('the_content', 'SomeMoreSentence');
//add_filter('the_content', 'SomeMoreSentence',11);// the bigger the number is ,the latter ..
?>