How can I check the post slug? - php

Question

Scenario: As you know, StackOverflow checks the title in the question. I mean when you open this URL:
http://stackoverflow.com/questions/38839016/should-i-store-the-result-of-an-function
automatically it will be replaced with this:
http://stackoverflow.com/questions/38839016/should-i-store-the-result-of-an-function-into-an-array
That replacement is because of being incomplete the first URL.
Ok well, I'm trying to make such a system by PHP. Here is my attempt:
// getting this from the URL
$id = '38839016';
// fetching this from database based on that id (38839016)
$real_title = $result['title'];
//=> Should I store the result of an function into an array
$real_title = str_replace("-"," ",strtolower($real_title));
//=> should-i-store-the-result-of-an-function-into-an-array
// getting whole uri
$current_uri = $_SERVER["REQUEST_URI"];
//=> /questions/38839016/should-i-store-the-result-of-an-function
What I want to do: I need to compare $real_title with title-part of the $current_uri. How can I determine "title-part"? It is everything which is after $id.'/' until / or ? or $ (end of string). How can I do that comparison?
And then:
if ( preg_match("//", $current_uri) ) {
// all fine. continue loading the page
continue;
} else {
// replace title-part of the $current_uri with $real_title
preg_replace("//", $real_title, $current_uri);
// redirect to this post with correct slug
header('Location: '.$_SERVER["HTTP_HOST"].);
}
briefly, I want to complete these:
if ( preg_match("//", $current_uri) ) {
preg_replace("//", $real_title, $current_uri);

Answer 1

Ok, in simple words, there is a good url and a requested url
if the requested url not equal the good url
redirect the visitor to the good one
<?
$id = '38839016';
$good_url = '/questions/'.$id.'/'.str_replace("-"," ",strtolower($result['title']));
preg_match( '/\/[0-9]+\/([a-z0-9-]+)\/.*/', $_SERVER[REQUEST_URI], $matches);
if ($matches[1] != str_replace("-"," ",strtolower($result['title'])))
header('Location: '.$good_url);