Syntax and variables

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
    <!DOCTYPE html>
    <html>
    <body><h1>My first PHP page</h1><?php
    echo “Hello World!”;
    ?>
    </body>
    </html>

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

PHP Variables


In PHP, a variable is declared using a $ sign followed by the variable name. Here, some important points to know about variables:

  • As PHP is a loosely typed language, so we do not need to declare the data types of the variables. It automatically analyzes the values and makes conversions to its correct datatype.
  • After declaring a variable, it can be reused throughout the code.
  • Assignment Operator (=) is used to assign the value to a variable.

Rules for declaring PHP variable:

  • A variable must start with a dollar ($) sign, followed by the variable name.
  • It can only contain alpha-numeric character and underscore (A-z, 0-9, _).
  • A variable name must start with a letter or underscore (_) character.
  • A PHP variable name cannot contain spaces.
  • One thing to be kept in mind that the variable name cannot start with a number or special symbols.
  • PHP variables are case-sensitive, so $name and $NAME both are treated as different variable.

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