How can case sensitivity in PHP functions impact the functionality of a script?

Case sensitivity in PHP functions can impact the functionality of a script because PHP function names are case-insensitive by default. This means that calling a function with a different case than its actual name will still execute the function. To avoid potential issues or confusion, it is recommended to use the correct case when calling PHP functions.

// Example of using correct case when calling a PHP function
$result = strtolower("Hello, World!"); // Using strtolower instead of STRTOLOWER
echo $result; // Output: hello, world!