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Developers ::
PHP
Resources :: Using Variables with
PHP
By Tom Fitzgerald
Defining
Variables
Taking our first lesson; Hello
World Example, we are going to spice it up a
bit and use variables with our PHP file. Let's
start right away by looking at an example then
explaining what we did.
<html>
<head>
<title>CCE's PHP
Tutorial</title>
</head>
<body>
<?php
$var = "PHP is cool";
echo "<p>$var</p>";
?>
</body>
</html>
As you can see the line we
really care about is
$var = "PHP is cool";
echo "<p>$var</p>";
This says define a variable
called $var and give
it the data of "PHP is
cool"; , then we simply display the data
using the echo
command.
Using
Constants
You saw above how to create
variables and display the data, now we are
going to take a look at creating 'constant '
variables. Constant variables typically do not
change. They work well at the top of document
if you know that you need to define something
that will not change, let's take a look at a
sample:
define("SALES_TAX",.05);
This creates a constant with the
name name and the
value is Tom
Fitzgerald. You'll notice that constants
do not require the $ before the variable name,
and variables are traditionally defined in all
upper case. This is not required but it can be
easier when reading your code so you know what
is a constant and what is not easily. You can
now view the value by doing...
echo SALES_TAX
Simple
Calculations
Now let's do some simple
calculations using our variables and
constant.
define("SALES_TAX",.05);
$Amount_Purchased = 5.45;
$Tax_Amount = $Amount_Purchased *
SALES_TAX;
This takes our constant
SALES_TAX and our
variable Amount_Purchased and multiplies
the two to get the tax amount.
Note: Make sure if
you are doing a calculation you are defining
the variable correctly, for
example:
This is the correct way
$Amount = 3
This is incorrect $Amount
= "3" ;
Quotes are used only
when defining a text variable or something
you don't want to ever run a
calculation on.
This is pretty simple so far so
lets just view some more simple
calculations:
$var1 = 3;
$var2 = 5;
$total = $var1 + $var2;
$total = $var1 * $var2;
$total = $var1 / $var2
This shows how we can do easy
addition, multiplication and division using our
new variables, good job.
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