PHP - Syntax
The syntax rules of PHP are similar to the C language. PHP is primarily a server-side scripting language used for web development. Let's dive into the details of PHP syntax.
PHP Syntax Overview
File Structure and Execution
A PHP code is typically stored in a text file with a ".php" extension. When opened in a browser with an HTTP protocol URL, the PHP code is executed by the server. PHP files may contain HTML, CSS, JavaScript, and PHP code blocks.
PHP Tags
Canonical PHP Tags
The most universally effective PHP tag style is:
<?php
// One or more PHP statements
?>
Using this style ensures correct interpretation of PHP tags.
Short-open (SGML-style) Tags
Short tags look like this:
<?php
// One or more PHP statements
?>
To enable short tags, you must either configure PHP with "--enable-short-tags" or set "short_open_tag=on" in php.ini.
Escaping from HTML
PHP code can be embedded within HTML documents using PHP tags. For example:
<p>This is a HTML statement</p>
<?php echo "This is a PHP statement."; ?>
<p>This is another HTML statement.</p>
PHP skips blocks outside PHP tags based on conditions, enhancing code readability and efficiency.
Basic Syntax
Statements
PHP statements are expressions terminated by semicolons (;). For example:
$greeting = "Welcome to PHP!";
Expressions
Expressions in PHP are combinations of tokens like numbers, strings, variables, constants, and keywords such as "if", "else", "while", "for", etc.
Blocks
Blocks of statements are enclosed in curly braces () to create logical structures. For example:
if (3 == 2 + 1) {
echo "Good - I haven't totally";
echo "lost my mind.";
}
Case Sensitivity
PHP is case sensitive, meaning variable names, function names, and other identifiers must match case exactly.
PHP syntax is crucial for building dynamic and interactive web applications. Refer to the PHP Manual for detailed syntax rules and examples.