PHP Basic Syntax

title: Basic Syntax

Basic Syntax

A PHP script can be placed anywhere in the document.

A PHP script starts with <?php and ends with ?>

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>


The output of that would be :

My first PHP page Hello World!

Note: PHP statements end with a semicolon (;).

Comments in PHP

PHP supports several ways of commenting:

<!DOCTYPE html> <html> <body> <?php // This is a single-line comment # This is also a single-line comment /* This is a multiple-lines comment block that spans over multiple lines */ // You can also use comments to leave out parts of a code line $x = 5 /* + 15 */ + 5; echo $x; ?> </body> </html>

PHP Case Sensitivity

In PHP, all 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 are legal (and equal):

<!DOCTYPE html> <html> <body> <?php ECHO "Hello World!<br>"; echo "Hello World!<br>"; EcHo "Hello World!<br>"; ?> </body> </html>

However; all variable names are case-sensitive.

In 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):

<!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>

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