Hello folks! welcome back to a new section of our tutorial on PHP. In this section of our PHP tutorial, we will be studying about the basic PHP Web concepts.
This tutorial guide illustrates how PHP can provide dynamic content according to web browser type, randomly generated numbers or User input. It also demonstrates how the client web browser can be redirected.
This tutorial guide illustrates how PHP can provide dynamic content according to web browser type, randomly generated numbers or User input. It also demonstrates how the client web browser can be redirected.
Identifying Browser and Platform
PHP creates some functional environment variable that can be seen in the phpinfo.php page that was used for setting up the PHP environment.
One of the environment variables that's set by PHP is the HTTP_USER_AGENT which is used to identify the user's web browser and operating system.
One of the environment variables that's set by PHP is the HTTP_USER_AGENT which is used to identify the user's web browser and operating system.
READ: PHP Arithmetic Operators
PHP provides a function getenv() to access the value of all environment variables. The information held in the HTTP_USER_AGENT is used in creating dynamic content that is appropriate to the browser.
Example
The following example shows how you can recognize a client's browser and operating system.
<html> <body> <?php function getBrowser() { $u_agent = $_SERVER['HTTP_USER_AGENT']; $bname = 'Unknown'; $platform = 'Unknown'; $version = ""; //First get the platform? if (preg_match('/linux/i', $u_agent)) { $platform = 'linux'; }elseif (preg_match('/macintosh|mac os x/i', $u_agent)) { $platform = 'mac'; }elseif (preg_match('/windows|win32/i', $u_agent)) { $platform = 'windows'; } // Next get the name of the useragent yes seperately and for good reason if(preg_match('/MSIE/i',$u_agent) && !preg_match('/Opera/i',$u_agent)) { $bname = 'Internet Explorer'; $ub = "MSIE"; } elseif(preg_match('/Firefox/i',$u_agent)) { $bname = 'Mozilla Firefox'; $ub = "Firefox"; } elseif(preg_match('/Chrome/i',$u_agent)) { $bname = 'Google Chrome'; $ub = "Chrome"; }elseif(preg_match('/Safari/i',$u_agent)) { $bname = 'Apple Safari'; $ub = "Safari"; }elseif(preg_match('/Opera/i',$u_agent)) { $bname = 'Opera'; $ub = "Opera"; }elseif(preg_match('/Netscape/i',$u_agent)) { $bname = 'Netscape'; $ub = "Netscape"; } // finally get the correct version number $known = array('Version', $ub, 'other'); $pattern = '#(?<browser>' . join('|', $known) . ')[/ ]+(?<version>[0-9.|a-zA-Z.]*)#'; if (!preg_match_all($pattern, $u_agent, $matches)) { // we have no matching number just continue } // see how many we have $i = count($matches['browser']); if ($i != 1) { //we will have two since we are not using 'other' argument yet //see if version is before or after the name if (strripos($u_agent,"Version") < strripos($u_agent,$ub)){ $version= $matches['version'][0]; }else { $version= $matches['version'][1]; } }else { $version= $matches['version'][0]; } // check if we have a number if ($version == null || $version == "") {$version = "?";} return array( 'userAgent' => $u_agent, 'name' => $bname, 'version' => $version, 'platform' => $platform, 'pattern' => $pattern ); } // now try it $ua = getBrowser(); $yourbrowser = "Your browser: " . $ua['name'] . " " . $ua['version'] . " on " .$ua['platform'] . " reports: <br >" . $ua['userAgent']; print_r($yourbrowser); ?> </body> </html>
Output
When the above example is executed, it will produce the below result on my computer. This result may be different on your various machines depending on what you are using -
Your browser: Google Chrome 54.0.2840.99 on windows reports: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36
READ: PHP Logical Operators
Display Images Randomly
The PHP rand() function is used to generate random number. This can generate random numbers with-in a given range. The random number generator should be sown so as to prevent a regular pattern of numbers being created. This is achieved by making use of the srand() function that specifies the seed number as its argument.
Example
Following example demonstrates how you can display different image each time out of four images -
<html> <body> <?php srand( microtime() * 1000000 ); $num = rand( 1, 4 ); switch( $num ) { case 1: $image_file = "/php/images/logo.png"; break; case 2: $image_file = "/php/images/php.jpg"; break; case 3: $image_file = "/php/images/logo.png"; break; case 4: $image_file = "/php/images/php.jpg"; break; } echo "Random Image : <img src=$image_file />"; ?> </body> </html>
Output
When the above example is executed, it will produce the following result -
READ: PHP Decision Making
Using HTML Forms
The most vital thing to notice when dealing with HTML forms and PHP is that any form element in an HTML page will automatically be available to your PHP scripts.
Example
Try the following example below by putting the source code in a test.php script -
<?php if( $_POST["name"] || $_POST["age"] ) { if (preg_match("/[^A-Za-z'-]/",$_POST['name'] )) { die ("invalid name and name should be alpha"); } echo "Welcome ". $_POST['name']. "<br />"; echo "You are ". $_POST['age']. " years old."; exit(); } ?> <html> <body> <form action = "<?php $_PHP_SELF ?>" method = "POST"> Name: <input type = "text" name = "name" /> Age: <input type = "text" name = "age" /> <input type = "submit" /> </form> </body> </html>
Output
When the above example is executed, it will produce the following result -
- The PHP default variable $_PHP_SELF is used for the PHP's script name and when you click on the "submit" button then same PHP script will be called.
- The method = "POST" is used to post user information to the server script. There are two methods to post data to the server script which are discussed in PHP GET & POST Methods tutorial.
READ: A Guide to PHP Arrays
Browser Redirection
The PHP header() function gives raw HTTP headers to the browser and can be used to redirect it to a new location. The redirection script should be at the very top of the page so as to prevent any other part of the page from loading.
The target is stated by the Location: header as argument to the header() function. After calling this function the exit() function can be used to halt parsing of rest of the code.
The target is stated by the Location: header as argument to the header() function. After calling this function the exit() function can be used to halt parsing of rest of the code.
Example
Following example demonstrates how you can redirect a browser request to another web page.
<?php if( $_POST["location"] ) { $location = $_POST["location"]; header( "Location:$location" ); exit(); } ?> <html> <body> <p>Choose a site to visit :</p> <form action = "<?php $_SERVER['PHP_SELF'] ?>" method ="POST"> <select name = "location">. <option value = "http://www.webdesigntutorialz.com"> Webdesigntutorialz.com </option> <option value = "http://www.google.com"> Google Search Page </option> </select> <input type = "submit" /> </form> </body> </html>
Output
When the above example is executed, it will produce the following result -
READ: Strings in PHP
Alright guys! This is where we are rounding up for this tutorial post. In our next tutorial guide, we will be discussing about the PHP GET and POST Methods
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Thanks for reading and bye for now.