Well, I don't know how much call there is for this and you can look at this as a very basic overview of how to start coding in PHP, if there is enough feedback I will expand it a bit more to try and help you guys learn how to code your own dynamic web pages.
Why use PHP?
Well, if you have dabbled in making web pages, you may have used HTML, and all it is really is a markup language to enable you to control the formatting and layout of pages.
The internet is said to exist in a "stateless protocol", The HTTP bit on the addresses for your web page stands for HyperText Transfer Protocol, you punch in an address, the address retrieves the HTML page back from the server... This is fine if you have a simple page that doesn't have any dynamic content.
Dynamic content?
Well, what if you were making an online store or a forum or a shoutbox or something where a user can interact with the page?
Because web pages were static, this should not normally be possible, we achieve log on and such with cookies and sessions and cheat our way around it..
Without going into how sessions and cookies work, we clearly need a way to pass variables and other parameters to our web pages and get them to generate different content depending on what we pass to it..
We're going to step into a little code, don't worry though, you don't need to grasp this quite yet, you just need to get the concept
Consider the following page:
http://www.dbfinteractive.com/downloadmenu.phpThe user is presented with a basic menu in which the search criterea can be adjusted.. The user clicks on "GO" and then the results are displayed.
This is not black magic, we need to look at the HTML source of that page to see what is going on so right click it, click on "view source" and inside the source you will come to this;
<form method="post" action="productions.php">
<br />
<center><b class="contactwhite">DISCLAIMER!!<br /></b>
<b class="contactdesc">We do our best to keep these downloads up to date, however we can't be expected to
trawl the message board to find your libs to add to the database, so when you release a new version or you update
your library, please use the contact page or the forums to let us know so that we can update the archive!
</b></center><br />
<center><b class="contactwhite">WHAT WOULD YOU LIKE TO SEARCH FOR?<br /><br /></b></center>
<b class="contactdesc">
<input type ='radio' name='search_value' value='1' >UTILITIES -- These are stand alone programs written to do menial tasks.<br />
<input type ='radio' name='search_value' value='2' >MUSIC REPLAY -- A wide selection of different replayers.<br />
<input type ='radio' name='search_value' value='3' >LIBRARIES -- Frameworks and libs to load gfx etc.<br />
<input type ='radio' name='search_value' value='4' >DX DLLS -- We keep a selection here to save you searching the net.<br />
<input type ='radio' name='search_value' value='5' checked='checked'>ALL -- This option will return everything above!
<center><br /><b class="contactwhite">ORDER SEARCH RESULTS:<br /><br /></b></center>
<b class="contactdesc">
<input type ='radio' name='search_order' value='1' checked='checked'>ALPHABETICAL -- Return your results alphabeticaly.<br />
<input type ='radio' name='search_order' value='2' >DATE RELEASED -- By the date that we think the download was released.<br />
<input type ='radio' name='search_order' value='3' >DATE ADDED TO DATABASE -- By the date added to our database.<br />
<input type ='radio' name='search_order' value='4' >MOST DOWNLOADED -- In order of popularity (most to least).<br />
<input type ='radio' name='search_order' value='5' >BY AUTHOR -- Returns them grouped by author.<br />
</b>
<center><br /><input type = "submit" class="input" value="-- GO! --" /></ center>
</form>
This is a standard HTML form with radio buttons and a submit button, the first thing to note is the first line..
<form method="post" action="productions.php">The method "post" quite literally "posts" the variables set by the form to the script contained in the action field. In this case, when submit is clicked the form will load a script called "productions.php", which in turn will access a database and construct a web page based on what the user chose..
The choices are contained in the variables "search_value" and "search_order".
The form is really simple, but you should be able to begin to see the benefit of php a little... The form calling a page that actually constructs another web page based on the values passed to it.
This is one of the reasons you will love php.
What is PHP?
PHP is a language that exists on your web server, the beauty of this is that it is platform independant, it will work with any computer that can display web pages and what it does is to process PHP commands and generate HTML code which is sent to the web browser.
It exists on the server, it is known as a "server side application" , Flash for example exists on the users computer and that is a "client side application".
We identify PHP pages by giving them a .PHP file extension as opposed to .html.
When we request a page like "index.php" this tells the server that the page contains php commands and must be processed by php before being served to the clients browser... You can mix php and html together so you can just drop in and out of php as you require, it really is as simple as that.
At a very simple level...
<?php
echo'<html>';
?>
<head>
</head>
<body>
<?
echo'</body>';
echo'</html>';
?>
This shows how you can mix html and php together, for this to work though we need to have php installed on our server and this file must have a .php extension.
You will notice two different sorts of tags.
<?php
?>
and
<?
?>
Both do exactly the same thing, these tags contain php code between them, both methods will work, the top method is considered to be the most correct.
You will see that php commands are terminated with semi colons in most cases, in the example we use the "echo" command.
This command sends code to the browser
So...
echo'</html>';
would send;
</html>
to the browser.
Pretty simple eh?
A few caveats...
consider the following html code...
<p>I wrote my first "hello world" program on a bitchin' CBM VIC 20 a long time ago</p>
This would cause problems because of the quotes..
Did you notice that those echo commands contained the code to be sent to the browser in quotes like this;
echo '<html code>' ;
?
You can in fact do both types of quotes...
echo '<html code>' ;
echo "<html code>" ;
Both will work, so if you had the like;
<p>i fuckin' love php</p>
Then you could legally send it to the browser like this;
echo"<p>i fuckin' love php</p>";
if you had the line;
<p>"hello world"</p>
You could do it like this;
echo '<p>"hello world"</p>';
Either way is cool.. Obviously you could just use straight HTML to do this but sometimes you will have to send stuff to the browser with php that contains both sets of quotes and you'll need to escape the quotes with the backslash like this;
echo "<p>\"hello world\"</p>";
This should be anough to get you interested in php, you do need a few more guidelines before getting started though.
Since PHP exists on the server then php pages MUST be accessed through the HTTP protocol, this is because the server has to process the php.
So, two options are open, you can etiher install php on your computer or you can upload your pages to your webspace.
I reccomend you use xampplite and install php on your computer,
http://www.apachefriends.org/en/xampp-windows.htmlGrab xampplite from there, extract the zip, click on "setup xampp"
then apache_start.bat
then mysql_start.bat
Then open your browser and type "localhost"
If you see the xampp welcome page then you have the thing working fine
Go into the htdocs directory and delete everything that you find in there.
When you drop your pages in that folder you can access them with "localhost"
The other thing that is really cool to type your code with is notepad++
http://notepad-plus.sourceforge.net/uk/site.htmThats the editor I use for all my web coding.
That should be enough to start you off, I will format it nicely when I get time, sorry for any errors.
Cheers,
Shockwave.
