Articles

Secure Include Files In PHP

8th July 2008 - 3 minutes read time

Including files in any PHP program is a very common practice and is nothing out of the ordinary. However, problems can occur when a user navigates to a script file that has a function, but is meant to be included as part of the larger program. For example, if your system includes a file to delete something then if that file is run by itself then there is a chance that it will delete everything.

Of course there are other factors like database access, global variables and sessions that would cause any script to simply error and not cause a problem. However, it is good practice to make sure that any include file is only run when it is included, and not when it is run on it's own.

The following little snipped of code can be placed at the top of any include files to make sure that it can't be run outside of an include. The file in this example would be called "test.php".

Quickest Way To Download A Web Page With PHP

7th July 2008 - 11 minutes read time

There are lots of different ways to download a web page using PHP, but which is the fastest? In this post I will go through as many different methods of downloading a web page and test them to see which is the quickest.

Here is a list of the different methods.

The PHP curl library.
Snoopy the PHP web browser. Bascially a wrapper for fsockopen.
fsockopen().
fopen() with feof().
fopen() with stream_get_contents().
file() and then implode().
file_get_contents() function.

Each method will be run and will retrieve the contents of a web page 50 times each in order to get a decent spread of times. On each run the time will be recorded into an array, this array will then be used at the end to calculate some statistics.

Randomise JavaScript Array

4th July 2008 - 3 minutes read time

Randomising a JavaScript array can be done in one or two ways. The easy way is to create a function that returns a random number and then use the sort() function of the Array object to sort the array by a random value.

// random number
function randNumber(){
 return (Math.round(Math.random())-0.5);
}
 
// create array
var numbers = new Array(1, 2, 3, 4, 5, 6, 7, 8, 9);
// print array
alert(numbers);
//randomise array
numbers.sort(randNumber);
//print random array
alert(numbers);

The sort function works by taking the randNumber function as a parameter. For every item of the array it uses this function to compare one value to the next. If the function returns a random number then the array will be sorted randomly.

The second method is slightly more complex and involves using the Fisher Yates randomising algorithm. The following function takes in an array and returns a randomly sorted array.

Merge Two JavaScript Arrays

3rd July 2008 - 1 minute read time

Here is a simple bit of code that you can use to merge one or more arrays. The function you need is called contact().

Take the following two arrays, both of which contain numbers.

var array1 = new Array(1,2,3,4);
var array2 = new Array(5,6,7,8);

To join these two arrays together we use the concat() function like this.

array1 = array1.concat(array2);

The variable array1 now contains the contents of both arrays.

Loading Page Styles And JavaScript With JavaScript

2nd July 2008 - 4 minutes read time

One good technique when using JavaScript is to load a single JavaScript file and get this file to load any other JavaScript or CSS documents that are needed. This means that you can simplify the instillation of a script on a page by including a single file, which then loads everything else it needs. Here is how to accomplish such a task.

The basic idea is that you add the references you need to the DOM structure of the document. Let's say that we want to load a CSS file called styles.css. To do this at run time we need to create a <link> element and give it some parameters before adding it onto the end of the <head> element of the page. Here is the code needed to do this.

Using JavaScript To Select Textarea Text

1st July 2008 - 2 minutes read time

This is a simple trick that will allow users to select the contents of a text area. First we need a text area.

<form><textarea name="textarea1" id="textarea1" rows="5" cols="40" wrap="off">This is some
long content.
This is some long content.
This is some long content.
This is some long content.
</textarea>
<br />
<input type="button" value="Select text" onclick="selectText('textarea1')">
</form>

This form also includes a button with an on click event that runs a function. This function takes a single parameter as the name of the element. It then sets the focus to this element and then selects all of the text therein.

Serialize And Unserialize With PHP

30th June 2008 - 3 minutes read time

If you have an object or array that you want to save until a later you can use the serialize() and unserialize() functions. The operation of the functions are straightforward. To serialize() an array just pass the serialise function the array like this.

$array = array(1,2,3,4);
$serializedArray = serialize($array);

Now when we print the serialized array out we get the following.

a:4:{i:0;i:1;i:1;i:2;i:2;i:3;i:3;i:4;}

This contains all of the data needed to recreate our array. Be careful not to edit this string because it will not work if you want to unserialize it and get the array back. You can store this string in a file or a database so that you can recreate the exact same array at a later date.

Use Alt+. To Print Out Last Parameter

27th June 2008 - 2 minutes read time

A handy trick when using a Unix/Linux system is to repeat the last parameter from the previous line. Lets say that you typed in the following line to move a file to another directory.

$ mv file.txt /usr/local/

To then move into that directory you can just type cd and Alt+. to copy in the last parameter used in the last line. This will put the following on the command line.

$ cd /usr/local/

You can press Alt+. multiple times to go back through your parameter history. Note that it only records the last parameter used for each line. So for the example above, if you pressed Alt+. twice you would get the last parameter of whatever command you executed before moving the file.

The PHP array_flip() Function And Detecting Functions

26th June 2008 - 3 minutes read time

The array_flip() function in PHP is used to swap the values of an array with the keys. Take the following array.

$array = array('key1'=>'value1', 'key2'=>'value2');

To exchange all the values with the keys we pass it through the array_flip() function.

$array = array_flip($array);
echo '<pre>'.print_r($array, true).'</pre>';

This prints out the following:

Array
(
 [value1] => key1
 [value2] => key2
)

If any of the values are the same then the highest key is overwritten. The following array:

$array = array('a', 'a', 'a', 'b');

Will produce the following array when passed through array_flip().

Print Out A Random Futurama Quote

25th June 2008 - 3 minutes read time

If you sent a curl request to the slashdot.org server you get back a random Futurama quote contained within the header information. The following curl command:

curl -Is slashdot.org

The commands supplied are I and s. I causes only the header of the file to be shown and s stops curl printing out anything. This returns the following headers:

HTTP/1.1 200 OK
Date: Wed, 25 Jun 2008 08:34:43 GMT
Server: Apache/1.3.41 (Unix) mod_perl/1.31-rc4
SLASH_LOG_DATA: shtml
X-Powered-By: Slash 2.005001
X-Bender: I'm an outdated piece of junk.
Cache-Control: private
Pragma: private
Connection: close
Content-Type: text/html; charset=iso-8859-1

Which contains a quote from Bender. To grab the correct line we then pass this through a regular expression to find a line that starts with an "X" and a dash, followed be either a B (for Bender) or an F (for Fry). The following line: