PHP Syntax
A PHP script is executed on the server, and the plain HTML result is sent back to the browser.
Basic PHP Syntax
A PHP script can be placed anywhere in the document.
A PHP script starts with <?php and ends with
?>:
<?php
// PHP code goes here
?>
The default file extension for PHP files is ".php".
A PHP file normally contains HTML tags, and some PHP scripting code.
Below, we have an example of a simple PHP file, with a PHP script that uses a
built-in PHP function "echo" to output the text
"Hello World!" on a web page:
Example
A simple .php file with both HTML code and PHP code:
<!DOCTYPE html>
<html>
<body>
<h1>My first PHP page</h1>
<?php
echo "Hello World!";
?>
</body>
</html>
Note: PHP statements end with a semicolon (;).
PHP Case Sensitivity
In PHP, keywords (e.g. if,
else, while,
echo, etc.), classes, functions,
and user-defined functions are not case-sensitive.
In the example below, all three echo statements below are equal and legal:
Example
ECHO is the same as echo:
<!DOCTYPE html>
<html>
<body>
<?php
ECHO "Hello World!<br>";
echo "Hello World!<br>";
EcHo "Hello World!<br>";
?>
</body>
</html>
Note: However; all variable names are case-sensitive!
Look at the example below; only the first statement will display the value of the
$color variable! This is because
$color, $COLOR, and
$coLOR are treated as three
different variables:
Example
$COLOR is not same as $color:
<!DOCTYPE html>
<html>
<body>
<?php
$color = "red";
echo "My car is " . $color . "<br>";
echo "My house is " . $COLOR . "<br>";
echo "My boat is " . $coLOR . "<br>";
?>
</body>
</html>