PHP

To desaturate an image means to remove all non-greyscale colours from it, essentially creating a black and white version. To do this you can use the function imagecopymergegray(), which is part of the GD image library. This function is a little difficult to figure out, but what is does is sample one image into another and optionally changing the amount of colours that are kept during the sampling process. The function can be made to sample just a section of the image, or the whole thing. The parameters of the function are as follows.

The Login Destination module is a neat little module that allows site admins to customize where the user will be sent to when they login. It provides a few of different ways of customizing, including a PHP snippet box that allows fine grained control.

What I needed to do on a recent project was to change the login destination for a single user role, but redirect everyone else to their user profile page. This required the use of the PHP snippet box. In order to get access to the current user object I had to include it into the scope of the PHP snippet code by using the following.

The FlashMessenger in Zend Framework has a bit of an odd name as it has nothing to do with Adobe Flash at all. It is a controller action helper defined in the class Zend_Controller_Action_Helper_FlashMessenger, which is used to store and retrive messages that are temporarily stored in the user's session. This is useful if you want to provide form validation and redirection at the same time as you can print out messages after the page has been loaded. If you are familiar with Drupal then this class acts in the same kind of way as the drupal_set_messages() function.

Because FlashMessenger is an action helper it can be initialized in a number of different ways, however, using the _helper property (the helper broker) of the controller is probably the easiest way. The FlashMessenger can be retrived through the helper broker in the following ways:

Question Take the following HTML form.

If you create classes in PHP then you should be unit testing them as much as you can. Setting up unit testing classes for your code can be time consuming and involve a bunch of copying and pasting. Thankfully, PHPUnit comes with a couple of helper functions that allow the creation of unit testing classes automatically, which can save a bit of copying and pasting.

As an example for this post I will use the following Spider class, which is part of some code I am working on at the moment to create a simple site spider in PHP.

I recently needed to create a function that would read and extract cookies from a Netscape HTTP cookie file. This file is generated by PHP when it runs CURL (with the appropriate options enabled) and can be used in subsequent CURL calls. This file can be read to see what cookies where created after CURL has finished running. As an example, this is the sort of file that might be created during a typical CURL call.

# Netscape HTTP Cookie File
# http://curl.haxx.se/rfc/cookie_spec.html
# This file was generated by libcurl! Edit at your own risk.

www.example.com        FALSE        /        FALSE        1338534278        cookiename        value

The first few lines are comments and can therefore be ignored. The cookie data consists of the following items (in the order they appear in the file.

Question

What does the $count variable equal after each of these loops?

Question

What does the following code do?

define("MY_CONSTANT", array(1,2,3,4,5));

Answer

If this code is run it will produce the following error:

Warning: Constants may only evaluate to scalar values in test.php on line x

This is because only scalar values can be assigned to constants. A scalar value is any integer, float, string or boolean value and does not include arrays, objects or resources. Trying to set any non-scalar value as a constant will produce this error.

Question

What is the difference between these two lines of code and can you produce the background code used for them?

Question

Write a PHP script that will print out the following text in the correct diamond shape.

    *
   ***
  *****
 *******
*********
*********
 *******
  *****
   ***
    *

Answer

The diamond shape consists of 10 'levels' of stars. Each level consists of one or more stars and some whitespace that pushes the middle star into the middle of the line. Each line must also consist of an odd number of stars as an even number of starts can't have a middle star.