PHP Variable Introduction

Variables

A variable is an area of memory which is set aside to store information , this is assigned an identifier by the programmer . You can recognise variables in PHP because they are prefixed with the dollar ( $ ) sign . To assign a variable you use the assignment operator ( = ) . Here is an example of this.

$name = "shedboy";
$intDaysInWeek = 7;

In the first example the variable identifier in this example is $name and the string value "iain hendry" has been assigned to it . In the second example the variable identifier is $intDaysInWeek and the number 7 is assigned to it . Note that in the number example we do not surround the variable with quotes in this way PHP treats this as a numeric value but if we had put quotes round it then PHP would have treated it as a string.

Variable Naming

There are some guidelines to follow for naming variables in PHP and these are as follows .
1. All variable names must begin with a letter or underscore character .
2 . The name of the variable can be made up of numbers , letters , underscores but you cant use charcters like + , - , & , ? , * , etc
One important thing to note if you are coming from another programming language there is no size limit for variables .

Case Sensitivity

One thing that causes many hours of hair pulling and anguish is case sensitivity , PHP is case sensitive (some languages are not) . Here is an example of what I mean.

$myname = "shedboy";
echo $Myname";
?>

Now we all know what we want to do , declare a variable , assign it the value of "shedboy" and then print this on the screen but in this example we have mis-spelt the variable name , when run the following error is displayed on the screen.

Warning: Undefined variable: Myname in D:testsample.php on line 3

Example

Using your favourite HTML editor enter the following

$url = "http://www.programmershelp.co.uk";
$rank = 1;
echo "Our favourite site is ".$url;
echo "
";
echo "It is numbered ".$rank;
?>

here is the output you should get

Our favourite site is
It is number 1