4. Understanding PHP Syntax and Tags
While PHP is embedded within HTML, it has strict rules regarding its own syntax.
Case Sensitivity
In PHP, variable names are case-sensitive, but built-in functions, keywords (if, echo, while), and class names are case-insensitive.
php
<?php $name = "Alice"; // $name $Name = "Bob"; // $Name (a different variable) echo $name; // Outputs Alice // Both work ECHO "<br>Using caps for echo."; eChO "<br>Using mixed case for echo."; ?>Statements and Semicolons
Every individual statement in PHP must be terminated with a semicolon (;). Forgetting the semicolon is one of the most common beginner errors.
php
<?php $x = 10; $y = 5; $sum = $x + $y; // Must end with a semicolon echo "The sum is: " . $sum; // The final statement ?>Note: Semicolons are not required after the closing PHP tag (?>) or after the closing brace of a block (}).
Comments
Comments are non-executable parts of the code used for documentation.
-
Single-line comments: php
<?php // This is a C++ style single-line comment # This is a shell-style single-line comment ?> -
Multi-line comments: php
<?php /* This is a comment block that spans multiple lines */ ?>