This series is about code in various languages that will calculate the distance between two latitudes and longitudes. This article is for the PHP code.

Code courtsey : GeoDataSource

/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*::                                                             :*/
/*::  This routine calculates the distance between two           :*/
/*::  points (given the latitude/longitude of those points).     :*/
/*::  It is being used to calculate the distance between two     :*/
/*::  locations using GeoDataSource(TM) Products                 :*/
/*::                                                             :*/
/*::  Definitions:                                               :*/
/*::    South latitudes are negative,                            :*/
/*::    east longitudes are positive                             :*/
/*::                                                             :*/
/*::  Passed to function:                                        :*/
/*::    lat1, lon1 = Latitude and Longitude of point 1           :*/
/*::                 (in decimal degrees)                        :*/
/*::    lat2, lon2 = Latitude and Longitude of point 2           :*/
/*::                 (in decimal degrees)                        :*/
/*::    unit = the unit you desire for results                   :*/
/*::           where: 'M' is statute miles                       :*/
/*::                  'K' is kilometers (default)                :*/
/*::                  'N' is nautical miles                      :*/
/*::  Worldwide cities and other features databases with         :*/
/*::  latitude longitude are available at                        :*/
/*::  http://www.geodatasource.com                               :*/ 
/*::                                                             :*/
/*::  For enquiries, please contact [email protected]      :*/
/*::                                                             :*/
/*::  Official Web site: http://www.geodatasource.com            :*/
/*::                                                             :*/
/*::         GeoDataSource.com (C) All Rights Reserved 2014      :*/
/*::                                                             :*/
/*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/

function distance($lat1, $lon1, $lat2, $lon2, $unit) {

  $theta = $lon1 - $lon2;
  
  $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
  
  $dist = acos($dist);
  $dist = rad2deg($dist);
  $miles = $dist * 60 * 1.1515;
  $unit = strtoupper($unit);

  if ($unit == "K") 
  {
    return ($miles * 1.609344);
  } 
  else 
  	if ($unit == "N") 
  	{
     	  return ($miles * 0.8684);
   	} 
    else 
    {
        return $miles;
    }
}

echo distance(32.9697, -96.80322, 29.46786, -98.53506, "M") . " Miles
";
echo distance(32.9697, -96.80322, 29.46786, -98.53506, "K") . " Kilometers
";
echo distance(32.9697, -96.80322, 29.46786, -98.53506, "N") . " Nautical Miles
";

Maxmind is providing IP Geolocation Database for free. Visit this page for the legacy database. And this page for the new database(work under process).

These are updated monthly. And there is no support.

Below piece of code can simulate a form submission through post method.

/******** The below header simulates Chrome Browser ********/

$header[0] = "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8";

$header[1] = "Accept-Language: en-US,en;q=0.8"; 
$header[2] = "Cache-Control: max-age=0";
$header[3] = "Connection: keep-alive";
$header[4] = "Host: www.doamin-name.com";

$header[5] = "User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.104 Safari/537.36";

$header[6] = "Referer: http://www.referrer-domain.com/"; 

/***********  end of header **********************/


$url = "http://www.doamin-name.com/page.php";
$param = "param=value1&submit=Submit"; // params that need to be passed
       
$ch = curl_init() or die(curl_error()); 
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $param);
curl_setopt($ch, CURLOPT_URL,$url);
curl_setopt($ch, CURLOPT_HTTPHEADER, $header); 

//curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1); // would be required if the return is going to be a binary file like image. From PHP ver 5.1.3 onwards the return is always binary so need not set this if PHP ver is >= 5.1.3

curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); //returns the received data in a variable. Must be on if CURLOPT_BINARYTRANSFER is set to 1 or true

//curl_setopt($ch, CURLOPT_COOKIE, 'PHPSESSID=' . $_COOKIE['PHPSESSID']); // if required. This sets Cookies to be sent with the request

$data1=curl_exec($ch) or die(curl_error($ch));
curl_close($ch);

If PHP Session Cookie needs to be retrieved from the result of the above request:

preg_match('/^Set-Cookie:\s*([^;]*)/mi', $data1, $m);
parse_str($m[1], $cookies);

echo $cookies['PHPSESSID'];

Mail-id verification:

/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/

Though both can be used in PHP and JS but there is another method to verify an email-id in PHP, by using the below code

if(!filter_var($email, FILTER_VALIDATE_EMAIL))

FILTER_VALIDATE_EMAIL is a predefined filter in PHP.
Name Verification:

/^[A-Za-z .'-]+$/

Phone Verification:

/^[0-9 -]+$/

Removing all spaces:

$pattern = '/\s+/';
$replace = "";
$string = preg_replace($pattern,$replace,$string);