Archive: PHP

Nobody enjoys the process of debugging their code. If you want to build killer web apps though, it’s vital that you understand the process thoroughly.

This article breaks down the fundamentals of debugging in PHP, helps you understand PHP’s error messages and introduces you to some useful tools to help make the process a little less painful.

Editor’s Note: We’ll be running workshops like “How to Build a Web App from A-Z” at The Future of Web Apps London.

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Recently I have been working on a WordPress plugin for Think Vitamin which necessitated getting back into the swing of PHP.

Whilst getting my head around how to create the plugin I started to delve into some of the core WordPress files and came across an unfamiliar yet syntactically sweet PHP control structure. It’s a simple if statement used in a file that combines PHP and HTML.

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There have been a ton of helpful and interesting tips posted to Tipster recently, so I thought we’d pull a few out for you all (and give the submitters a bit of well-deserved publicity).

Topics that we’re covering are: MySQL, CSS, JavaScript, PHP, JQuery, life hacks and server admin.

MySQL Geo Search

Here’s a MySQL statement to search for nearest objects to you in a database, ‘lat’ & ‘lng’ are fields in the ‘items’ table with the location of object and $latitude & $longitude are the users location. The distance field will be the calculated distance in Km between the user and the object:

SELECT *,(((acos(sin((".$latitude."*pi()/180)) * sin((`lat`*pi()/180))+cos((".$latitude."*pi()/180)) * cos((`lat`*pi()/180)) * cos(((".$longitude."- `lng`)*pi()/180))))*180/pi())*60*1.1515*1.609344) as distance FROM `items` ORDER BY distance;

By: Sam Machin
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Transparent background images – PNG fix for IE6 – a few reminders

When using the MS filter (via The AlphaImageLoader) to fix PNG transparency for IE6 — in your CSS, remember to:

1. Set width and height for the element/s containing the transparent background image.
2. First set background to none — then apply filter for background image.
3. Apply ‘position: relative;’ to any contained links to ensure functionality

(Also, bear in mind that the background images can no longer be tiled or positioned via ‘background-position’).

By: Prisca
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Address Longitude and Latitude in Google Maps

Google maps does not show the Longitude and Latitude of an address you search. To get this information, enter this piece of JavaScript into you browsers address bar and hit enter:

javascript:void(prompt('',gApplication.getMap().getCenter()));

A little window will then pop-up displaying the Longitude and Latitude for you. Bingo!

[Editor's note: If you add this to your bookmarks toolbar, it's even easier to use. Just click it whenever you're on Google Maps. Hat tip to Phil Balchin.]

By: Pete Roome
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Custom Details in Code Hints – Zend Studio for Eclipse

Zend Studio is a brilliant platform for PHP development. In my view, well worth the cost. One of the best things about it now being built on Eclipse is the project-wide code hinting.

When you see the built-in code hints and highlight an option, you get loads of lovely details regarding the functions and classes that you are about to use… as you would expect from most modern IDEs. However, Zend Studio for Eclipse takes this further for your own classes and functions!

When you have written your classes and functions, start placing a multi-line comment just above the opening line, i.e. /**, hit Return and Studio will prompt you for data types and descriptions for your method variables.

This is invaluable in understanding those classes you wrote at 3:47am, 3.5 years ago and haven’t used since!

By: Simon Hamp
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Use a Print Stylesheet

Print stylesheets allow you to change the style of your page when printing, without having to provide a separate “print version” of the markup.

You specify a print CSS by adding “media=’print’” as an attribute to the link tag.

<link rel="stylesheet" type="text/css" media="print" href="print.css"/>

In the print CSS you should remove unnecessary elements such as sidebars, menus, background colours, presentational images, etc so as not to waste ink and paper on parts which don’t need to be printed. You can also change the font and size to make sure the text is clear on the printed page.

You can even add some CSS to show the URLs of links on the page, which wouldn’t normally be seen when printing.

a[href]:after { content: " (" attr(href) ") "; }

By: Rich Adams
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Make your links easier to read

Instead of using { text-decoration: underline; } on your links (as browsers do by default) use:

{ border-bottom: 1px solid; }.

This makes your links easier to read, as there will be more space between the text and the line underneath, so the line will no longer cross through your ‘y’s and ‘g’s.

You can also then style your underline with all the usual border stylings, much more exciting than a plain underline :)

By: Laura Kalbag
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Manual filmstrips in jQuery

Really simple manual photo film-strip in jQuery. Used to swap a large image on a page with that of a thumbnail elsewhere on the page, such as different photos of a product in an e-commerce store.


$(document).ready(function(){
imageSwapper(".thumbnails a");
});



function imageSwapper(link) {
$(link).click(function(){
$('#largeimage').attr('src', this.href);
return false;
});
};


Just link the thumbnails to their larger versions and pop them in a div or paragraph of class thumbnails, and give the large image an ID of large image, and you are good to go!

By: Michael Peacock
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Store user passwords as salted hashes

Just using a hash of the user password is not strong enough. If two users have the same password, they’ll have the same hash. Dictionary attacks are also still possible as the attacker can have a list of dictionary word hashes. Using a salted hash involves generating a random string of characters, which you then concatenate with the password before hashing. Two users with the same password will then have different hashes, and the stored hash will never just be a hash of a common word if the user chose a weak password. You then store the salt, and the hashed value in your database.

hash_to_store = sha1(salt + real_pass)

There are many different methods you could use too, such as concatenating the salt with a hash of the password and then hashing that, etc.

hash_to_store = sha1(sha1(real_pass) + ...

By: Rich Adams
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CD/DVD stuck in Macbook

Having gotten a DVD stuck inside my Macbook the other day, i found the only way to force eject it was to hold down the trackpad button on reboot. DVD popped right out.

By: Pete Roome
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Photo credit: flickr.com/photos/mance