Unveiling Constants

Constants are immutable values, unlike variables that can change during script execution.

Examples of Constants

1. Defining Constants

    define('PI', 3.14159);
    define('COMPANY_NAME', 'Awesome Inc.');
    

2. Using Constants

    echo "Circle with radius 5 has area: " . PI * 5 * 5 . " square units.";
    echo "
";
    echo "Welcome to " . COMPANY_NAME . "!";
    

These examples demonstrate how constants ensure consistency and maintainability:

• PI remains fixed, preventing typos or accidental modification.
• COMPANY_NAME can be easily updated across the entire script.

Key Differences from Variables

• Value immutability: Constants cannot be changed after definition, whereas variables can.
• Global scope: Constants are accessible from anywhere in the script, while variables typically have specific scopes.
• Case sensitivity: Constants are case-sensitive by default, unlike most variables (except case-sensitive variable names).

Leveraging constants effectively enhances code readability, maintainability, and consistency.