| |
|
|
PHP Tutorial
Part 7 - Final Notes
Introduction
In
the past 6 parts of this tutorial I have shown you the
basics of writing PHP. In this final part I will show
you a few small things which don't really warrant a
section of their own.
Comments
As
with any programming language, it is quite important to
comment in your script. If you are working on a script
with someone else you must let them know what you code
does and if you are distributing your script you will
need to show people how to edit it. Even if you are the
only one who will use your script it is useful to
comment so that you can edit it at a later
date.
In PHP there are two ways you can comment.
One way is used for single line comments and the other
is used mainly for comments that go over one line. A
single line comment is written as follows:
// Your comment can go in
here
Everything after the // will be
ingnored when the script is executed. You can even place
these on the end of another line e.g.
print "Hello $name"; //
Welcome to the user
Another way of
commenting is by using multi-line comments:
/* The following piece of
code will take the input
the user gave and will check
that it is valid before
adding it to the database
*/
Anything between the /* and the */ will
be ignored. It is important that you always close this
type of comment as not doing so could make your script
not work.
Print, Echo and
HTML
As you may have noticed
during this tutorial I have actually used 4 different
ways of outputting information to the browser:
echo("Text here");
echo
"Text here";
print("Text here";
print "Text
here";
To clarify, all of these do the
same thing and you can use any or all of them in a
script. There is no reason to even use the same type all
through a script. The only problem you may find is that,
as I explained in part 2, all the " in the HTML code
must be replaced with \" which, if you have a lot of
code, could take a very long time. This brings me to a
very useful part of PHP. If, for example, you created
the header of a page dynamically in PHP, then had the
static page and finally a dynamic footer you can do the
following:
<?
Top PHP code in
here
?>
HTML Code
<?
Bottom PHP code
in here
?>
This gets even better as
the PHP code will just continue from where it was left
off so you could do the following:
<?
IF Statement
{
?>
HTML For IF Being Correct
<?
}
else {
?>
HTML For IF Being
Wrong
<?
}
?>
You must
always remember to close IF statements and loops,
though, as it is very easy to forget.
One Line
Prints
Being able to place HTML
code into your PHP is very useful, but what happens if
you want to put the value of a variable into the code.
Unlike when using an echo or print statement, you can't
just put in the variable name as this section is not
actually part of the PHP code. Instead you must just put
in a little PHP.
For example if you wanted to
print someone's name from a script with HTML formatting
you would do the following:
<font face="Arial" size="7"
color="red"><b><? echo($variablename);
?></b></font>
In the above
code you have just added in the following PHP:
<? echo($variablename);
?>
Which is exactly the same as the
following PHP code:
<?
echo($variablename);
?>
But
all put onto one line.
Conclusion
This
tutorial has given you some of the basics of PHP and
should allow you to do most things you will want to. For
a much more in depth look you should visit PHP.net, the
official homepage of PHP. One major omission of this
tutorial, you may have noticed, is using PHP with a
database. As this is one of the major reasons that
people use PHP and because there are many options
I
will put this in a separate PHP/MySQL tutorial.
© 1999 - 2001
David Gowans
|
|
.gif)
.gif)