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 “
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:
<!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.
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:
<!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 are treated as three different variables:
<!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>