Adam R Brown

Variables in PHP

A variable holds data. This data might be a number, a string (i.e. text), or something more complex (like an array or object, which is beyond the scope of this tutorial). Variables are always written with a dollar sign at the beginning. To keep things easy, I recommend using only letters (case sensitive!) and maybe numbers in your variable names.

To create a variable, just assign it a value. For string values, you must enclose the value in 'apostrophes' or "quotes". Note that every line ends with a ; (semicolon).

Good examples of variables, illustrating the string, integer, and boolean data types:

<?php
$myVar1 = 'Hello!';  // The word Hello! saved as a string
$myVar2 = '1'; // the number 1 saved as a string (note the apostrophes)
$myVar3 = 1; // the number 1 saved as an integer (note the lack of apostrophes)
$myVar4 = 'true'; // the word true saved as a string
$myVar5 = true; // the boolean (logical) value of true. Frequently used booleans are true, false, and null.
?>

Bad examples that will cause a “parse error” in PHP:

<?php
$myVar = 'Hello; // No closing apostrophe
$myVar = "Hello'; // If you start with " you must end with "
$myVar = "Hello" // No ending semicolon
$myVar = 'How's it going?'; // see explanation below
?>

The last example really throws people off. PHP sees that the string starts with ', so when it sees the ' after How, it thinks that’s the end of the string, so it can’t figure out what to do with s it going. The result: A fatal parse error. There are two ways to fix it:

<?php
$myVar = 'How\'s it going?'; // escape the ' with a backslash
$myVar = "How's it going?"; // use " instead of ' to delimit the string
?>

To display the contents of a (string or integer) variable on your webpage, you just echo it:

<?php
$myVar = 'Wuzzup, man?';
echo $myVar;
print $myVar; // note that print and echo do the same thing
?>

To append something to an existing variable, use a dot. There are two ways to do this:

<?php
// method #1
$myVar1 = 'Hey dude. ';
$myVar1 .= 'How are you?; // $myVar1 now holds "Hey dude. How are you?"

// $method #2
$myVar2 = 'Hey man. ';
$myVar3 = 'How are you?';
$myVar4 = $myVar2 . $myVar3; // $myVar4 holds "Hey man. How are you?"
?>

We’ll have a little more to say about variables in the next section.