Articles

You can display your latest Wordpress posts anywhere on your site by using an RSS reader called SimplePie and a few lines of code. SimplePie is a fast and efficient RSS reader, and it will also cache feeds to reduce the amount of processing time taken.

Download simple pie from the website and upload the simplepie.inc file to your web server. Next include the following section of code anywhere on your site that you want to display the latest post on.

When you supply files that web browsers can open they are usually opened inside the browser, rather than being downloaded. This can be annoying, especially where PDF documents are involved. You could supply the files in a compressed format in order to force users to download them, but this is also annoying as the user then has to uncompress the file.

You can force the web browser to supply the file as a download by using the header() function in PHP. The following little bit of code will take any filename and supply it as a download.

<?php
$file = $_GET['file'];
header('Content-type: octet/stream');
header('Content-disposition: attachment; filename='.$file.';');
header('Content-Length: '.filesize($file));
readfile($file);
exit;
?>

All you have to do is link to this script with the argument being the file name you want your users to be able to download.

When writing JavaScript applications I normally write for loops like this.

for (var i = 0; i < elements.length; ++i) {
  // loop...
}

There isn't anything wrong with this, but it is not an efficient way of doing things. All it takes is a little knowledge of what the for loop does every time it runs. The loop can be split into three sections like this.

For most functions it is normal for have the function return the output of a calculation. With PHP it is also possible to pass values to the function by reference. A better way of saying this is rather than pass the value of the variable you pass a pointer to the variable itself. When you do this anything that you do to the variable inside the function is also done outside, so if you interact with the variable again it will contain a different value.

The ampersand (&) character is used in the parameters of the function to stipulate that a parameter will be passed by reference.

Here is an example of this at work.

Use the following function to list the contents of one or more nested directories.

function recursive_directory($dirname,$maxdepth=10, $depth=0){
 if ($depth >= $maxdepth) {
  return false;
 }
 $subdirectories = array();
 $files = array();
 if (is_dir($dirname) && is_readable($dirname)) {
  $d = dir($dirname);
  while (false !== ($f = $d->read())) {
   $file = $d->path.'/'.$f;
   // skip . and ..
   if (('.'==$f) || ('..'==$f)) {
    continue;
   };
   if (is_dir($dirname.'/'.$f)) {
    array_push($subdirectories,$dirname.'/'.$f);
   } else {
    array_push($files,$dirname.'/'.$f);
   };
  };
  $d->close();
  foreach ($subdirectories as $subdirectory) {
    $files = array_merge($files, recursive_directory($subdirectory, $maxdepth, $depth+1));
  };
 }
 return $files;
}

Use this in the following way.

Try running the following PHP script.

<?php
 echo 'browser output';
 session_start();
?>

You will either see normal output or get the following error messages.

This is because when you try to start the session it adds items to the headers outputted by the browser, including the setting up of cookies. To stop this happening you need to ensure that the session_start() function call is put before any output from the browser. This is the case for all header modifying functions including set_cookie() and header().

The set_error_handler() function can be used in PHP to allow you to catch any run time errors and act accordingly. This function can take two parameters:

• Error Handler : This a string which is the name of the function that will be called if an error is encountered.
• Error Types (optional) : This is an optional parameter used to tell PHP on what error codes to act. This is the same error reporting setting.

The function that is defined in the function must have the following footprint as a minimum.

function handler($errno,$errstr)

You can also get a lot more information out by using other parameters.

function handler($errno,$errstr,$errfile,$errline,$errcontext)

Here is some code that will print two errors to screen with as much information as possible.

Appending arrays in PHP can be done with the array_merge() function. The array will take any number of arrays as arguments and will return a single array. Here is an example using just two arrays.

$array1 = array('item1', 'item2');
$array2 = array('item3', 'item4');
$array3 = array_merge($array1, $array2);
print_r($array3);

Will print out.

Array
(
 [0] => item1
 [1] => item2
 [2] => item3
 [3] => item4
)

You can also create arrays using the array command inside the parameter list.

The following code loads the contents of a text file and randomly displays a line from it. You can use this to display a random quote on a page every time it loads.

$file= "quotes.txt";
$quotes = file($file);
srand((double)microtime()*1000000);
$randomquote = rand(0, count($quotes)-1);
echo $quotes[$randomquote];

It works by loading a file into memory and picking a line from that file at random. Here is a sample file you might want to use.

This is the first quote - Person One
This is the second quote - Person Two

Fill this with your own quotes and you are away.

Creating a simple highlight effect is quite easy when you use the JavaScript framework mootools.

The first thing to do is grab the mootools library from the site and link it in your web page. You can select different components with mootools, but if you grab the whole thing you can start to play with whatever you want. Put this line of code in the head section of your web page.

<script type="text/javascript" src="mootools.js"></script>

For this example I want the highlight to occur when the page has finished loading. So I use the window.addEvent function to add an action for the 'domready' event to the window object of the page.