PHP Structure

All of the PHP code within one web page is considered to be one PHP "script". You are free to break up the code into multiple <?php ... ?> sections, as needed. For example, we might set a variable containing today's date at the beginning of a page, which is then used for output later in the page. Let's call our ongoing example script worldpeace.php3. Note that PHP pages usually have the filename extension .php3, as that is the default filename that the web server will look for. This can be changed by reconfiguring the web server.

worldpeace.php3:

<?php
 $today=getdate(time());
?>
<H2>Today's Headline:</H2>
<P ALIGN="center">
 <?php
  print "World Peace Declared";
 ?>
</P><HR>
<!-- begin footer -->
 <SMALL>Today is <?php
  print $today[weekday];
  ?></SMALL>
 

We haven't yet discussed the PHP language itself, so let's focus on structure for now. The above page contains a small section of PHP code, which assigns a value to a variable $today. A second block of PHP code in the middle of the page outputs our headline, and a third block of PHP near the end of the page uses the $today variable to output the day of the week. Given that today (the day I'm writing this, not necessarily the day you're reading it!) is Wednesday, the above code would produce the page:

Besides breaking up PHP code into multiple blocks, it is also possible to include code from external files into your pages. Sometimes you wish to keep bits of code in its own file -- for instance, HTML code that makes up a repeating element such as a logo or footer, or PHP code that makes up a function that you might want to use in several different pages. Returning to the previous example, suppose we break out the footer into its own file, and the initial PHP block into its own file:

setdate.php3:
<?php
 $today=getdate(time());
?>

footer.php3:
<!-- begin footer -->
<SMALL>Today is <?php
 print $today[weekday];
?></SMALL>

Now, we can use PHP's include() function to pull the above files into our example page:

<?php
 include ("setdate.php3");
?>
<H2>Today's Headline:</H2>
<P ALIGN="center">
 <?php
  print "World Peace Declared";
 ?>
</P><HR>
<?php
 include ("footer.php3");
?>

The most common use for the include() function is, as seen above, to reuse certain components across several pages. Of course, your components will often contain much more code than the examples seen here! Also notice that each component is treated as an HTML page -- that is, it can contain HTML tags and any PHP code must appear within the <?php ... ?> tags.

The Very Basics
Welcome to PHP
Scalar Variables and Data