Explanation of PHP Basic Syntax --New to PHP

Php is a language that is very much like writing c. The best feature of PHP versus c is that it is designed primarily to be used on WebPages -- allowing the author to intermingle their php code and the HTML on the same page. Being able to mix these two languages together provides a very flexible environment that allows the author to code some very nice dynamic content. PHP is called a server side scripting language. Unlike a computer language such as C++, Visual Basic, Java and others, php does not require the programmer to have a traditional compiler. Instead PHP interprets the code and sends it back to the web server. This is sometimes referred to as JIT -- just in time compiling.

The Webserver in turn serves up a webpage that is formatted according to the instructions found in a php script and sends it to the client that requested it (usually a web browser running on a home pc or laptop). Using a language like php for web scripting makes it possible for a web designer to create a single page that can return completely different content every time a user leaves and then returns.

This is usually accomplished by embedding variables into hyperlinks or by using input text boxes. When the user clicks on the embedded links, the variables coded into those links is sent out to the webserver. You have probably noticed that when you click some links and look up in your web browser - there is this a long string of characters that looks something like this like this:

http://mrarrowhead.com/index.php?page=php_passing_variables.php

Notice the question mark right there after "index.php." the question mark tells the server to start looking for variables to parse (or interpret). Next, in the example link above, there is the "page" variable with an equals sign between it and "php_passing_variables." When this link is clicked the php script that the thenlinks points to loads into the user's web browser retrieving the "page" variable which is stored in a global variable array called $_GET.

The "page" variable looks like this $_GET['page']; to the programmer. This is called the GET method.

There are several other mtypes of varibles that you will become aquainted with as you learn php web programming.

• Post
• Get
• Get
• Cookie

Now, let’s go over some basic php syntax. The first thing to cover is how to jump into and out of php code from within your webpage’s HTML.

Notice from the example above that you must start all of your PHP code with

and it is ended with

?>

These two tags let the webserver running PHP know what parts of a web page are php code. Also notice that at the end of the echo statements, there is a semicolon. Semicolons in php tell the compiler when a line of code has been read and another line is about to start. Each simicolone signifies the end of a line of code.

The semicolon can be included on the same line but php will still treat it as the end of a line.

The next section will cover php code blocks and variable data types.