How to know if an array key is the last one?

Question

PHP

Hello!
There is this code:

class Handler {
  public static function go_to($url, $parametrs = NULL)
  {
    if (isset($parametrs))
    {
    foreach ($parametrs as $key => $value)
    {
      if (count($parametrs) > 1)
      {
          $params .= $key.'='.$value.'&';
      }
      else
      {
        $params = $key.'='.$value;
      }
    }
    }
    if (isset($parametrs))
    {
      return header('Location: /'.$url.'?'.$params.'');
      exit();
    }
    else
    {
      return header('Location: /'.$url.'');
      exit();
      }
  }
}

Usage:

<?php
Handler::go_to('index', array('succcess' => '20', 'r' => '29312'));
?>

It is intended for redirecting by the link specified in the $url variable with the specified $params. The problem is that at the end of the url in the address bar remains & (which is not surprising). I want to remove it. I suppose that for this you need to check if the array key is the last one. But how can this be done?

Answer 1

Discover: http_build_query

Answer 2

With the end() function

if (count($parametrs) > 1){
         if(end($parametrs) === $value)
           $params .= $key.'='.$value;
         else
          $params .= $key.'='.$value.'&';
      }

Answer 3

Is it possible through implode()?
foreach ($parametrs as $key => $value)
{
$params = implode('&', array($params, $key.'='.$value));
}