| |
|
|
PHP Tutorial
Part 2 - Displaying Information &
Variables
Introduction
In
the last part of the tutorial I explained some of the
advantages of PHP as a scripting language and showed you
how to test your server for PHP. In this part I will
show you the basics of showing information in the
browser and how you can use variables to hold
information.
Printing
Text
To output text in your PHP
script is actually very simple. As with most other
things in PHP, you can do it in a variety of different
ways. The main one you will be using, though, is print.
Print will allow you to output text, variables or a
combination of the two so that they display on the
screen.
The print statement is used in the
following way:
print("Hello world!");
I
will explain the above line:
print is the command
and tells the script what to do. This is followed by the
information to be printed, which is contained in the
brackets. Because you are outputting text, the text is
also enclosed instide quotation marks. Finally, as with
nearly every line in a PHP script, it must end in a
semicolon. You would, of course, have to enclose this in
your standard PHP tags, making the following
code:
<?
print("Hello
world!");
?>
Which will
display:
Hello world!
on the
screen.
Variables
As
with other programming languages, PHP allows you to
define variables. In PHP there are several variable
types, but the most common is called a String. It can
hold text and numbers. All strings begin with a $ sign.
To assign some text to a string you would use the
following code:
$welcome_text = "Hello and welcome to
my website.";
This is quite a simple line
to understand, everything inside the quotation marks
will be assigned to the string. You must remember a few
rules about strings though:
Strings are case
sensetive so $Welcome_Text is not the same as
$welcome_text
String names can contain letters,
numbers and underscores but cannot begin with a number
or underscore
When assigning numbers to strings you
do not need to include the quotes so:
$user_id =
987
would be allowed.
Outputting
Variables
To display a variable
on the screen uses exactly the same code as to display
text but in a slightly different form. The following
code would display your welcome text:
<?
$welcome_text =
"Hello and welcome to my
website.";
print($welcome_text);
?>
As
you can see, the only major difference is that you do
not need the quotation marks if you are printing a
variable.
Formatting Your
Text
Unfortunately, the output
from your PHP programs is quite boring. Everything is
just output in the browser's default font. It is very
easy, though, to format your text using HTML. This is
because, as PHP is a server side language, the code is
executed before the page is sent to the browser. This
means that only the resulting information from the
script is sent, so in the example above the browser
would just be sent the text:
Hello and welcome to
my website.
This means, though, that you can
include standard HTML markup in your scripts and
strings. The only problem with this is that many HTML
tags require the " sign. You may notice that this will
clash with the quotation marks used to print your text.
This means that you must tell the script which quotes
should be used (the ones at the beginning and end of the
output) and which ones should be ignored (the ones in
the HTML code).
For this example I will change
the text to the Arial font in red. The normal code for
this would be:
<font face="Arial"
color="#FF0000">
</font>
As
you can see this code contains 4 quotation marks so
would confuse the script. Because of this you must add a
backslash before each quotation mark to make the PHP
script ignore it. The code would chang
e to:
<font face=\"Arial\"
color=\"#FF0000\">
</font>
You
can now include this in your print statement:
print("<font
face=\"Arial\" color\"#FF0000\">Hello and welcome to
my website.</font>");
which will
make the browser display:
Hello and welcome to my
website.
because it has only been sent the
code:
<font
face="Arial" color="#FF0000">Hello and welcome to my
website.</font>
This does make it
quite difficult to output HTML code into the browser but
later in this tutorial I will show you another way of
doing this which can make it a bit easier.
Part
3
In part 3 I will introduce If
statements.
© 1999 - 2001
David Gowans
|
|
.gif)
.gif)