Posted by: Shofiur Rahman

Posted on: July 4, 2012 3:46 pm

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The basic four steps to generate an image using PHP are as follows:

  • Creating a canvas image on which to work.
  • Drawing Shapes or printing text on that canvas.
  • Outputting the final graphic
  • Cleaning up resources.

Sample PHP script:

// Creating a canvas image

$height = 200;

$width = 200;

$im = imagecreate($width, $height);

$white = imagecolorallocate($im, 255, 255, 255);

$black = imagecolorallocate($im, 0, 0, 0);

// Drawing Shapes or printing text

imagefill($im, 0, 0, $black);

imageline($im, 0, 0, $width, $height, $white);

imagestring($im, 4, 50, 150, 'Label text', $white);

// Output image

header('Content-type: image/png');

imagepng($im);

// Clean up

imagedestroy($im);

?>

Posted by: Shofiur Rahman

Posted on: June 27, 2012 4:32 pm

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To authenticate a user includes the following steps:

  • Identifying visitors
  • Implementing access control
  • Authentication

Identifying Visitors

The web is fairly anonymous medium, but it is often useful to know who is visiting your site to focus on right business area. You are able to get little about the visitors due to users privacy. With a little work server can find out quite lot about users computers, networks, browsers, etc.  From visitor’s IP address you are able to know visitor’s geographic location.

Implementing access control

Simple access control is not difficult to implement. A simple PHP script is shown below.

<?php
//create short names for variables

$name = $HTTP_POST_VARS['name'];

$password = $HTTP_POST_VARS['password'];

if(empty($name) || empty($password)){

//Visitor needs to enter a name and passwor.

?>

<strong>Please Log In</strong>

<form method=”post” action=”login.php”>
<label>User Name: </label> <input type=”text” name=”name” />
<label>Password:</label> <input type=”password” name=”password” />
<input type=”submit” value=”Log In” />

</form>

<?php

}

else if($name==’user’&& $password==’pass’){

//login successful

}

else {
//login failed
}

?>

Encrypting passwords

To secure the access control you need to implement encryption algorithm on the user login. The PHP function crypt () provides a one-way cryptographic hash function. The prototype for this function is

String crypt (string str [, string salt])

Basic Authentication in PHP

There are some built-in authentication facilities in to HTTP. Scripts or web servers can request authentication from a web browser. The web browser is then responsible for displaying a dialog box or similar device to get required information from the user.

PHP scripts are generally cross-platform, but using basic authentication relies on environment variables set by the server.  A sample of HTTP basic authentication using PHP is shown below.

<?php
// if we are using IIS, we need to set $PHP_AUTH_USER and $PHP_AUTH_PW

if(substr($SERVER_SOFTWARE, 0, 9) == ‘Microsoft’ && !isset($PHP_AUTH_USER) && !isset($PHP_AUTH_PW) && substr($HTTP_AUTHORIZATION, 0, 6) == ‘Basic’)
{

list($PHP_AUTH_USER, $PHP_AUTH_PW) = explode(‘:’, base64_decode(substr($HTTP_AUTHORIZATION, 6)));

}

//Replace this if statement with a database query or similar

if($PHP_AUTH_USER!=’user’ || $PHP_AUTH_PW != ‘pass’)

{

// Visitor has not yet given details, or their
// name and password combination are not correct

header(‘WWW-Authenticate: Basic realm=”Realm-Name”‘);
if(substr($SERVER_SOFTWARE, 0, 9) == ‘Microsoft’)
header(‘Status: 401 Unauthorized’);

else
header(‘HTTP/1.0 401 Unauthorized’);

echo ‘You are not authorized to view this resource.’;

}

else {

// visitor provided correct details.

}

?>

Posted by: SEO Positive

Posted on: November 29, 2010 11:55 am

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All developers have to transfer sites at some point, if you don’t I envy you. It seems that site transfers always have teething issues with the difference in server builds, operating systems having different compilations of PHP and the rest.

And worst of all, different hosts limitations…

But to transfer a site you need to make a simple list of things that need to be done in order for it to work.

  • Get all files, including hidden files (many a time I’ve been caught up on the .htaccess on a mac being hidden and a site riddled with 404 errors…)
  • Get all database details of the new server
  • Update all calls to databases
  • Use Dream Weaver (for the only things its any good for) to search and replace across the site for the old URL and change it to the new one, and the same with database details)
  • Make sure image, stylesheet, javascript and any other call is base root not an absolute URL (unless externally hosted)
  • Upload everything, including creating the new databases
  • Test everything, fix bugs and teething issues

If you can do all of the above your site will transfer easy peasy.

Posted by: SEO Positive

Posted on: November 24, 2010 1:22 pm

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Every developer knows just how many if and else statements are needed for validation, data checks, state checks, etc.

And they take up a lot of space and cause necessary amounts of code, this tutorial is about to teach you a way to make your if and else statements all on one single line.

Ternary Operator

The ternary operator is an if else statement compressed to one single line using the ? and : operands, see below for an example ternary operator

$apples = ( $colour == 'green' ) ? 'Tasty green apples' : 'Nasty rotten apples' ;

The above is the exact equivalent to the below:

if( $color == 'green' ) {
       $apples = 'Tasty green apples';
}
else {
      $apples = 'Nasty rotten apples';
}

Which we can all agree is far more troublesome and big, some people say that an if and else statement is easier to read than a ternary operator. It can be argued until man steps foot on Mars its a personal preference thing. Personally, I use the ternary operator wherever possible but sometimes its not possible. See below for an example that you couldn’t use a ternary operator for:

if ( $database->row_result == 'something' ) {
       $database->row_result = substr ( $database->row_result, 0, 100 );
       $this->some_cool_function( $database->row_result );
       return validate_the_above ( );
}
else {
       throw new RunTimeException ( 'the result was in a malformed state' );
       exit;
}

The reason the above will not work in a ternary operator is the required state involves multiple lines of code in order to finish the operation (whatever yours is) and a ternary operator will only handle function calls, variable setting and validation.

In essence the ternary operator is a great getter and setter method (until PHP6 is released with C style getters and setters).

But what if you only wanted to validate something was there and use the else?

Since PHP 5.3 they have made this shortcut available see below for an example.

$apples = ( $colour == 'brown' ) ?: 'Nasty rotten apples';

Notice the above has no true statement and will only set in the event of a false validation.

Posted by: SEO Positive

Posted on: November 22, 2010 9:18 am

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Anyone asking for the ability to pull data off another website or to globalise a collection of links or anything you want will come across the file_get_contents function. This function is very useful for data scraping or for generalising a collection of links or general content.

The function itself does nothing but puts the source of the web page you supply it into a string available for use throughout your script.

It does have sister functions such as file() which puts the source code into an indexed array (a new array element for every line of code) and CURL.

While there are a huge number of solutions to doing this, file_get_contents is for me the easiest as with regular expressions its unstoppable.

To use file_get_contents():

$data = @file_get_contents( "http://www.bbc.co.uk/" );
if( $data ) echo htmlentities( $data );

The above will output the source code of the very latest BBC home page (with html entities so you get the source not just a reconstructed bbc home page)

Using regular expressions you can pull any piece of data throughout the source code.

Posted by: SEO Positive

Posted on: November 5, 2010 8:51 am

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The world of the internet is edging toward the search engines, there is nothing more important than the search engines available to the world wide web and with the web turning ever more dynamic its also becoming harder to build a search engine friendly website.

But the clever guys at apache managed to create a solution for us called mod_rewrite

What is mod_rewrite?

mod_rewrite is a technology used to mask “ugly URL’s” into search engine friendly alternatives using the clever regular expressions engine.

Whats an ugly url?

An ugly URL would be:

www.seopositive.com/?page=10

If there are ugly url’s there are pretty urls?

yes, there are pretty urls these are what mod_rewrite achieve.

So how do I do this?

Well there are literally hundreds of mod_rewrite rule generators out there to help you turn your site into an search engine monster and for content management systems such as wordpress you can generalise your rules.

But the first step is to create a file called .htaccess in the root of your website, for a CMS such as wordpress the rules are

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

The above doesn’t look like much but it makes the difference between an ugly url, non search engine friendly and generally SEO fail website into what could be an SEO monster.

Once you have put all the necessary rules into your .htaccess file. Save it, close it, upload it and test your websites pretty urls.

Posted by: SEO Positive

Posted on: November 3, 2010 9:12 am

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Method chaining is becoming an increasingly popular technique in the programmers world, but not a lot of people understand it.

This short tutorial will hopefully shed light on:

  1. what it is
  2. what it does

So what is method chaining?

To answer this question I have to show you some basic classes, see below for a standard class and method set.

class random_functions{
     function format($string, $f = 'uppercase'){
            switch($f){
                 case 'uppercase':
                       $string = strtoupper($string);
                 break;
                 case 'lowercase':
                       $string = strtolower($string);
                 break;
             }
             return $string;
     }
     function strings($string, $filter = 'trim'){
            switch($filter){
                  case 'trim':
                         $string = trim($string);
                  break;
                  case 'mres':
                         $string = mysql_real_escape_string($string);
                  break;
             }
             return $string;
      }
}

To use the above class, instantiation is the usual

$functions = new random_functions();
echo $functions->strings($functions->format($string, 'lowercase'), 'mres');

Which, to me at least, looks awful, its hard to read and just generally not very easy to work with.
What method chaining allows us to do is keep our functions separate and make our re-usable code a lot easier to read and understand as this requires a lot of logical thought in to how you want it to work and even makes planning easier due to having to put your functions in the correct order to achieve what you want.

See below for the same class that allows method chaining.

class random_functions{

     static $output = '';

     function format($string, $f = 'uppercase'){
            switch($f){
                 case 'uppercase':
                       self::$output = strtoupper($string);
                 break;
                 case 'lowercase':
                       self::$output = strtolower($string);
                 break;
             }
             return $this;
     }
     function strings($string = '', $filter = 'trim'){
            switch($filter){
                  case 'trim':
                         self::$output = $string ? trim($string) : trim(self::$output);
                  break;
                  case 'mres':
                         self::$output = $string ? mysql_real_escape_string($string) : mysql_real_escape_string(self::$output);
                  break;
             }
             return $this;
      }
      function output($in = ''){
             echo $in ? $in : self::$output;
             return $this;
      }
}

And the use of this is much clearer and much easier, see below for the use and an explanation of the code.

$functions = new random_functions();
$functions->format('Foo Bar', 'lowercase')->strings()->output();

As you can see, there are arrows between each function call, this is called method chaining. This helps us keep our code clean, semantic and easy to read and understand.

Lets analyze the code

In order to make things easier I added a class variable to work from, this variable is available to every function within the class and I use it to validate input to functions and give us something to work from and around if needed. I also changed each return.

Instead of returning our formatted string, I’ve changed each return to $this what $this means is “the current object” which in a class means the class object.

The class object?

Classes are objects, with children (the methods/functions within the class) and to make any function chainable within a class all you have to do is return an object. You cannot make static methods chainable i.e

class random_functions{

     static $output = '';

     static function format($string, $f = 'uppercase'){
            switch($f){
                 case 'uppercase':
                       self::$output = strtoupper($string);
                 break;
                 case 'lowercase':
                       self::$output = strtolower($string);
                 break;
             }
             return $this;
     }
    static function strings($string = '', $filter = 'trim'){
            switch($filter){
                  case 'trim':
                         self::$output = $string ? trim($string) : trim(self::$output);
                  break;
                  case 'mres':
                         self::$output = $string ? mysql_real_escape_string($string) : mysql_real_escape_string(self::$output);
                  break;
             }
             return $this;
      }
     static function output($in = ''){
             echo $in ? $in : self::$output;
             return $this;
      }
}

random_functions::format('Foo Bar', 'lowercase')::strings()::output();

Will not work, this will return a fatal error.

But to make a static method chainable you must return a new object as $this is undefined in a static method as the parent becomes self

We hope that you enjoyed this tutorial and its helped you understand the ideology of method chaining and how it is useful.

Posted by: SEO Positive

Posted on: October 6, 2010 8:16 am

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Continuing on from a previous post about page speed, anything built in PHP beyond something simple should be class based to prevent duplication of code and keep your web pages  as small as possible.

But what are PHP Classes?

Well PHP Classes ventures into the OOP area (That’s Object Orientated Programming) and a class is a collection of functions, variables and general behavior depending on your class structure.

This is an example of a PHP class.

//mordor.php
class my_precious
{
         public static function mordor($ring = null)
         {
                   if($ring !== 'ring') return "Well... Where's the ring? I don't want your {$ring}";
                   else return 'Well... That\'s all evil taken care of... Gratz';
         }
}

So as you can see, its fairly simple to do. Really its just keeping your code in one collated name space, without the above code being in a class the most efficient way to deal with that would be to build a whole line of if and else statements to capture any data on any page you wanted to display your Mordor paddy.

Of course when you’re building massive projects classes may seem a lot more efficient but the above code was a syntax example. To use the above code, all you need on any page is the below code.

require 'mordor.php';
echo my_precious::mordor('Cheese and ham Toastie');

Which we’ll all agree is a lot less hassle than writing a script and copy and pasting it all over every page you want the validation/script to run on. Having to only put 2 lines of code into a page will keep your page sizes down and involves a lot less on page server action with if and else statements littered everywhere to catch and modify data in and out of the page.

While procedural code may have some advantages for building a website with PHP, unless its a single query and including an entire class and its children is entirely arbitrary PHP Classes are the way to go forwards.

Happy coding!

Posted by: SEO Positive

Posted on: September 28, 2010 8:28 am

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So many PHP developers, in no limited skill set generally lack the knowledge of the APC which is an acronym for Alternate PHP Cache. And cutting a long story short the APC is a virtual memory storage to keep your variables in while retaining them across multiple web pages, and throughout your code.

It is a great way of speeding up, and minimizing your code, if used correctly. When I first began using it, I was almost scared of its technicality but I was reassured after a quick read on php.net (your best friend, as a PHP developer.)

The PHP is, largely, not installed as a default module on every server and the module will be need to be installed if you want take advantage of it.

The functions you’re more than likely to use are:

  • apc_store($name, $value, $time=null);
  • apc_fetch($name);
  • apc_delete($name);
  • apc_exists($key);

apc_store($name, $value);

This function, as you might imagine, Does nothing more than store a variable into the APC for arrays of objects you do need to alter the way that you instantiate your array object. See below for an example:

$myArray[] = new foo();//assuming these classes do nothing but echo their namespaces and PHP_EOL
$myArray[] = new bar();// " "
//now lets store it.
apc_store('arrayObject', new ArrayObject($myArray));
//and fetch it.
$apcElement = apc_fetch('arrayObject');
//and output it all.
var_dump($apcElement);

The output will be along the lines of

foo
bar

but in essence, the storing of objects isn’t recommended as you will not store the information, simply the properties of that object.

apc_fetch($name);

So assuming we have used apc_store(‘foo’, ‘bar’); we can now use apc_fetch(‘foo’); see the example below

//set
apc_store('foo', 'bar');
//get
apc_fetch('foo');
//will output "bar"

Which as you can see, is incredibly easy to use. Overall, the usability of the APC is almost perfect.

apc_delete($delete);

This is, again, very simple to use and self explanatory.

//set
apc_store('foo', 'bar');
//get
var_dump(apc_fetch('foo'));
//delete
apc_delete('foo');
//get, to test
var_dump(apc_fetch('foo'));

again, very simple, precise and to the point.

And lastly, of the functions you’re most likely to use. The validation of a properties existence within the APC.

apc_exists($key);

This simple validation checks whether or not the key you have supplied exists within the stored apc array. See below for usage instructions.

if(apc_exists('foo')) echo 'the property exists within the APC ' . PHP_EOL;
else echo 'The property does not exist, try setting it?' . PHP_EOL;

This is a very simple validation example, and I can’t stress enough that these examples shouldn’t be used in a live environment, simply learn from them and if you get stuck, remember, php.net is your best friend.

Posted by: SEO Positive

Posted on: July 13, 2010 8:02 am

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As a PHP Programmer you’re more than likely to build countless login scripts and constantly have to use sessions and cookies. Lets face it, they’re great for temporarily storing data for use all over your site/application.

But you always hit that snag, why isn’t it working? I can’t set or fetch the session variable or delete that darn cookie! Hours later you realise it was simple, this is a simple PHP tutorial for any session and cookie fans out there.

When you’re using PHP sessions, you must ALWAYS use session_start(); at the top of every page, yes, even above all of the HTML tags or use session_start(); in an include/require file (if you’re using external scripts)

Simply put, when debugging $_SESSION and $_COOKIE the below code, is actually your best friend

session_start();
print_r($_SESSION);
print_r($_COOKIE);

This will print out all of the current items, if they’re available stored within these “superglobals” which are actually just arrays of data that your browser stores.

If you don’t see anything for $_SESSION, you probably didn’t have a session_start(); at the beginning of the referring page, and if you don’t see anything for $_COOKIE it wasn’t set, see below for how to set and delete a cookie as there are multiple ways of destroying cookie data I will show you my preferred method.

$days = 14;//this cookie will last for 14 days
setcookie('Cookie_Name', 'Cookie_Data', time() + ($days * 24 * 60 * 60));
//and to delete a cookie, I use this
setcookie('Cookie_Name', '');

This should all help you’re $_SESSION and $_COOKIE headaches, developers will all panic from time to time as to why their application is not working. And well, its the simple things that make the difference.

Next time, using the APC (Alternate PHP Cache)

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